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7OL. XVI .NO. 1 




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JANUARY, 1931 

The Society of Motion Picture Engineers 

Its Aims and Accomplishments 

The Society was founded in 1916, its purpose as expressed in its 
constitution being "advancement in the theory and practice of mo- 
tion picture engineering and the allied arts and sciences, the standardi- 
zation of the mechanisms and practices employed therein, and the 
maintenance of a high professional standing among its members." 

The Society is composed of the best technical experts in the 
various research laboratories and other engineering branches of the 
industry in the country, as well as executives in the manufacturing 
and producing ends of the business. The commercial interests also 
are represented by associate membership in the Society. 

The Society holds two conventions a year, one in the spring and one 
in the fall, the meetings being generally of four days' duration each, 
and being held at various places. At these meetings papers are pre- 
sented and discussed on all phases of the industry, theoretical, tech- 
nical, and practical. Demonstrations of new equipment and methods 
are often given. A wide range of subjects is covered, and many of the 
authors are the highest authorities in their distinctive lines. 

Papers presented at conventions, together with discussions, 
contributed articles, translations and reprints, abstracts and abridge- 
ments, and other material of interest to the motion picture engineer 
are published in the Journal of the Society. 

The publications of the Society constitute the most complete ex- 
isting technical library for the motion picture industry. 




Volume XVI JANUARY, 1931 Number 1 



Condenser and Carbon Microphones Their Construction and 

Use W. C. JONES 3 

Microphone Concentrators in Picture Production 


Tests of Motion Picture Screens WILLIAM F. LITTLE 31 

Dubbing and Its Relation to Sound Picture Production 


Three Color Sub tractive Cinematography 


Double Toning of Motion Picture Films 

Some Causes for Variations in the Light and Steadiness of High 

Intensity Carbons D. B. JOY AND A. C. DOWNES 61 

An Estimate of the Present Status and Future Development of 

the Home Talkies 


Methods of Securing a Large Screen Picture 80 

Report of Secretary 86 

Committee Reports 90 

Abstracts 114 

Patent Abstracts 117 

Officers 120 

Committees 121 

Contributors to This Issue 123 

Society Notes 125 





Associate Editors 




Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members $12.00 per year; to members $9.00 per year; single 
copies $1.60. Order from the Society of Motion Picture Engineers, Inc., 20th and 
Northampton Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 


W. C. JONES** 

Summary. Of the numerous microphones which have been developed since Bell's 
original work on the telephone, only two are used extensively in sound recording for 
motion pictures, namely, the condenser microphone and the carbon microphone. 

The condenser microphone was first proposed in 1881 but owing to its low- sensi- 
tivity was limited in its field of usefulness until the development of suitable amplifiers. 
In 1917 E. C. Wente published an account of the work which he had done on a con- 
denser microphone having a stretched diaphragm and a back plate so designed as 
to introduce an appreciable amount of air damping. The major portion of the 
condenser microphones used today in sound recording embody the essential features 
of the Wente microphone. Marked progress has, however, been made in the design 
and construction of these instruments with the result that they are not only more 
sensitive but also more stable. The factors which contribute to this improvement 
are described in detail in this paper. Recently a number of articles have appeared 
in the technical press calling attention to certain discrepancies between the conditions 
under which the thermophone calibration of the condenser microphone is made and 
those which exist in the studio. The nature of these discrepancies and their bearing 
on the use of the microphone are discussed. 

Microphones in which the sound pressure on the diaphragm produces changes in 
the electrical resistance of a mass of carbon granules interposed between two electrode 
surfaces have been used commercially since the early days of the telephone. In 
recent years the faithfulness of the reproduction obtained with the carbon micro- 
phone has been materially improved by the introduction of an air damped, stretched 
diaphragm and a push-pull arrangement of two carbon elements. This instrument 
is finding extensive use in sound recording and reproduction fields where carbon 
noise is not an important factor. The outstanding design features of the push-pull 
carbon microphone are described in this paper and suggestions made as to the pre- 
cautions to be taken in its use if the best quality, maximum life, etc., are to be obtained. 

Of the numerous microphones which have been developed since 
Bell's original work on the telephone, only two are used extensively in 
sound recording for motion pictures, namely, the condenser micro- 
phone and the carbon microphone. It has, therefore, been sug- 
gested that it would be fitting to review at this time the construction 
of these instruments and consider some of their transmission char- 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Bell Telephone Laboratories, Inc., New York, N. Y. 

4 W. C. JONES [J. S. M. P. E. 

acteristics and the precautions which should be exercised in their 

Condenser Microphone. In 1881 A. E. Dolbear 1 proposed a tele- 
phone instrument which could be used either as an electrostatic 
microphone or receiver. This instrument consisted of two plates 
insulated from one another and clamped together at the periphery. 
The back plate was held in a fixed position whereas the front was 
free to vibrate and served as a diaphragm. It is obvious that if 
the diaphragm were set in vibration by sound pressure, the electrical 
capacitance between the two plates would be changed in response 
to the sound waves, and if a source of electrical potential were con- 
nected in series with the instrument a charging current would flow 
which would be a fairly faithful copy of the pressure due to the sound 
wave. Apparently Dolbear realized that the current developed in 
this way would be minute, for in the telephone system which he 
proposed as a substitute for the one using Bell's magnetic instru- 
ments he employed the electrostatic instrument only as a receiver 
and adopted the loose contact type of microphone. At approxi- 
mately the same time an article appeared in the French press 2 calling 
attention to the use of a condenser as a microphone and commenting 
on the fact that this type of microphone had been found to be less 
sensitive than the loose contact type. 

Owing to the low sensitivity of the condenser microphone, the 
field of usefulness of this instrument was extremely limited for a 
number of years and it did not assume a position of importance 
among the instruments used in acoustic measurements and sound 
reproduction until suitable amplifiers had been developed. The 
development of the vacuum tube amplifier, however, filled this need. 
In 1917 E. C. Wente 3 published an account of the work which he 
had done on an improved condenser microphone having a stretched 
diaphragm and a back plate so located relative to the diaphragm 
that, in addition to serving as one plate of the condenser, it added 
sufficient air damping to reduce the effect of diaphragm resonance 
to a minimum 4 . The response of this instrument was sufficiently 
uniform over a wide range of frequencies to make it not only useful 
in high quality sound reproduction but a valuable tool in acoustic 
measurements in general. 

The major portion of the condenser microphones used today in 
sound recording embody the essential features of the Wente micro- 
phone. Marked progress has, however, been made in the design 

Jan., 1931] 


and construction of these instruments since the initial disclosure and 
it will no doubt be of interest to many to consider briefly the nature 
of this advance. 

In the early microphones employing air damping the diaphragm 
was composed of a thin sheet of steel which was stretched to give 
it a relatively high stiffness. When assembled in the microphone 
the stiffness was further increased by that of the air film between 
diaphragm and the damping plate with the result that the resonant 
frequency was well above the frequencies which it was desired to 
transmit and the diaphragm vibrated in its normal mode over a wide 
frequency range. In such a structure the mechanical impedance for 

FIG. 1. Western Electric Company's 394 type condenser microphone. 

frequencies below resonance is due almost entirely to stiffness reac- 
tance. Hence a constant sound pressure produces substantially 
the same displacement of the diaphragm at all frequencies within 
this range and uniform response results except at the very low fre- 
quencies where an appreciable reduction in the stiffness of the air 
film occurs. The effective mass of a steel diaphragm is, however, 
relatively large and necessitates a comparatively high stiffness to 
secure the desired resonant frequency. From the standpoint of 
securing maximum sensitivity of the microphone, i. e., displacement 
of the diaphragm per unit force, it is of course important to make 
the stiffness as low as possible and employ as small a value of mechani- 
cal resistance as is consistent with the degree of damping required. 


[J. S. M. P. E. 

An improvement in both respects can be effected by decreasing the 
mass of the diaphragm, for with a reduced mass a given resonant 
frequency can be obtained with lower values of stiffness and the 
desired damping constant secured with less mechanical resistance. 

The aluminum alloys have therefore replaced steel in the dia- 
phragms of most of the condenser microphones in use today. A 
typical example of such a microphone is the Western Electric Com- 
pany's instrument (394 type) shown in the photograph, Fig. 1, and 
the cross-sectional view, Fig. 2. The diaphragm of this instrument 
is made from aluminum alloy sheet 0.0011 inch in thickness. The 








FIG. 2. Cross-sectional view of the 394 type condenser microphone. 

edges are clamped securely between threaded rings, gaskets of softer 
aluminum being provided to prevent damage at the clamping surfaces. 
The requisite stiffness is obtained by advancing the stretching ring 
until a resonant frequency of 5000 cycles is obtained. The method 
of determining the resonant frequency of the diaphragm is as follows. 
The diaphragm assembly to be tested is coupled to a condenser micro- 
phone which is provided with a suitable circuit for measuring its 
output. A special telephone receiver is placed in contact with the 
diaphragm on the side opposite to the coupler. Current from a 
vacuum tube oscillator is then passed through the winding of the 
receiver, setting up eddy currents in the diaphragm under test. 


The forces which are developed as a result of the reaction of the mag- 
netic field produced by the eddy currents and that of the permanent 
magnet of the receiver set the test diaphragm in motion. The reso- 
nant frequency is determined by noting the frequency at which 
the output from the condenser microphone is a maximum. 

In the early Wente microphone the damping plate was a continuous 
surface. Subsequent work by I. B. Crandall 5 showed that the re- 
quired amount of damping at the resonant frequency could be ob- 
tained without adding unduly to the impedance at other frequencies 
by cutting grooves in the plate. This reduced the stiffness introduced 
by the air film and decreased the irregularity in response at low fre- 
quencies previously mentioned. The grooves in the damping plate of 
the Western Electric Company's 394 type microphone are cut at 
right angles. Holes, tapered at the outer end to reduce resonant 
effects, are bored through the plate at the intersection of the grooves 
to form connecting passages between the air film at the front and 
the cavity at the back. In order to prevent the resonance which 
would result if the grooves extended into the portion of the chamber 
surrounding the damping plate, the outer ends are closed by an 
annular ring which is pressed over a shoulder on the plate. The 
surface of the damping plate is plane within 8 X 10 ~ 5 inch. The 
departure from a plane in any individual case is determined com- 
mercially by the interference pattern developed when an optically 
flat plate is placed over the damping plate under test. 

A duralumin spacing ring 0.001 inch in thickness separates the 
damping plate from the diaphragm. It is essential that all dust and 
dirt be excluded from this space. To prevent foreign material 
from entering through the holes in the plate a piece of silk is fastened 
over the outer surface. The assembly of the diaphragm and damp- 
ing plate is made in a dust-proof glass cabinet. 

If the back wall of the condenser microphone were rigid, changes 
in the separation between the damping plate and the diaphragm of 
sufficient magnitude to affect not only the sensitivity of the instru- 
ment but also its frequency response characteristic would result 
from variations in barometric pressure. Complete compensation 
for these changes in pressure can only be obtained by permitting 
free interchange of air between both sides of the microphone dia- 
phragm. This is, however, objectionable owing to the fact that 
sufficient moisture is likely to be introduced to start corrosion and 
affect the insulation between the damping plate and the diaphragm. 



[J. S. M. P. E. 

A compensating diaphragm of organic material has therefore been 
introduced which prevents this undesirable effect of humidity but 
is sufficiently low in stiffness to equalize the changes in pressure 
encountered in the normal use of the microphone. 

In order to prevent transmission losses at voice frequencies due to 
the presence of the compensating diaphragm, an acoustic valve is 
inserted between the damping plate and this diaphragm. This 
valve consists of a disk of silk clamped between two aluminum plates 
of unequal diameters. Gas in passing from the damping plate to the 
compensating diaphragm moves laterally from the edges of the smaller 
plate through the silk to a hole in the center of the larger plate. The 
impedance of this path is high at voice frequencies but low enough 






FIG. 3. Cross-sectional view of the thermophone 
and the condenser microphone. 

for steadily applied pressure differences to permit compensation 
for changes in barometric pressure. 

After the damping plate and diaphragm are assembled the space 
between the clamping rings is filled with beeswax to make the joints 
gas-tight and exclude moisture. A hole is, however, provided for 
filling the microphone with nitrogen. The purpose of the nitrogen 
is to prevent corrosion of the damping plate and diaphragm surfaces 
and eliminate any reduction in pressure due to oxidation of the 
sealing compound. 

It has been customary for some time to determine the response 
characteristics of a condenser microphone by the thermophone 
method. 6 In making this measurement the diaphragm of the micro- 



phone is coupled acoustically to the thermophone in the manner 
shown in Fig. 3. The thermophone consists of two strips of gold 
foil which are mounted on a plate and fit into the recess in the front 
of the microphone. Capillary tubes are provided for filling the 
space enclosed between the plate and the microphone diaphragm 
with hydrogen. This is done in order to make the wave-length of the 
sound developed in the recess as large as possible compared with 
dimensions of the chamber. If this were not the case the sound 
pressure at different positions in the chamber would not be in phase 
and the conditions on which the computations of the magnitude 
of the sound pressure are based would not be met. A direct current 
of known value is passed through the foil. Super-imposed upon 
the direct current is an alternating current of the desired frequency 
which causes fluctuations in the temperature of the foil and in the gas 
immediately surrounding it. These fluctuations in temperature in 

- 55 


O db = 1 














= ' 








100 1000 IOOC 

FIG. 4. 


Pressure calibration of the 394 type condenser microphone. 

turn cause changes in the pressure on the microphone diaphragm. 
The magnitude of the pressure developed on the diaphragm can be 
computed from the constants of the thermophone and the coupling 
cavity, and the voltage developed by the microphone for a given pres- 
sure determined with suitable measuring circuits. 7 Obviously, such a 
calibration affords a measure of the response of the microphone in 
terms of the actual pressure developed on the diaphragm and is 
independent of the external dimensions of the instrument. Hence, 
it does not take into account any effect which the microphone may 
have on the sound field when used as a pickup instrument for re- 
cording or broadcasting purposes. The thermophone calibration is 
often referred to as a "pressure" calibration and the response ob- 
tained by placing the instrument in a sound field of constant pressure, 
a "field" calibration. A thermophone calibration of a representative 
Western Electric 394 type condenser microphone is shown in Fig. 4. 



[J. S. M. P. E. 

For many of the uses to which the condenser microphone is put, 
for example, the calibration of head type telephone receivers, the 
conditions under which it operates agree with those under which the 
thermophone calibration is made. There are, however, cases where 
this agreement does not exist, for when a microphone is inserted in a 
sound field of uniform intensity the pressure on the diaphragm may 
depart rather widely from a constant value in certain frequency 
ranges. Several articles 8 have recently appeared calling attention 
to this discrepancy between the pressure and field calibrations and 
pointing out that a pressure calibration of a microphone may not be 
entirely representative of its performance under the conditions which 
exist in a studio. 

The difference between the pressure and field calibrations is due to 
several factors. In the first place the sound is diffracted around 


k (k * t 

f 6 cf o 

O db - 1 VOLT (OPEN 

200 VOLTS 















100 1000 


FIG. 5. Field calibration of the 394 type condenser microphone for a 
direction of approach of sound normal to the diaphragm. 

the microphone differently at different frequencies. At frequencies 
where the wave-length is large as compared with its external dimen- 
sions the pressure is the same as that of the undisturbed wave. 
At the higher frequencies where the microphone is large in comparison 
with the wave-length of the sound, the pressure is twice that developed 
at the lower frequencies. In the 394 type microphone the effect of 
diffraction first becomes noticeable in the region of 1200 cycles and 
reaches a maximum of 6 db. at approximately 2200 cycles. The 
second factor which causes a difference between the pressure and 
field calibrations is acoustic resonance in the shallow cavity in front 
of the microphone. This causes the pressure actuating the dia- 
phragm to be higher than that of the incident sound wave in the fre- 
quency region of 1500 to 5500 cycles. The maximum increase in 
pressure occurs at approximately 3500 cycles. If the sound source 

Jan., 1931] 



is so located relative to the microphone that the waves approach 
from a direction normal to the diaphragm and reflection from sur- 
rounding walls and objects is negligible, the combined effect of diffrac- 
tion and resonance is to produce a maximum departure from flatness 
of approximately 12 db. as is shown by the field calibration, Fig. 5. 9 
If the sound wave travels along the diaphragm the effective pressure 
is reduced at the higher frequencies due to difference in phase. 
Hence, if the direction of approach of the sound wave is parallel to 
the plane of the diaphragm, the departure from flatness is materially 
reduced. This is brought out quite clearly by the field calibration 
for sound approaching from a direction parallel to the diaphragm, 
Fig. 6. 9 

The discrepancy between the pressure and field calibrations of the 





p - rv> * o 


* ^ 

- , 

















FIG. 6. Field calibration of the 394 type condenser microphone for a 
direction of approach of sound parallel to the diaphragm. 

condenser microphone involves two important assumptions, namely, 
a plane sound wave and no reflection from walls or surrounding 
objects. When the microphone is used in a studio much of the sound 
reaches the diaphragm by way of reflection from the walls of the room. 
The requirement of no reflection is therefore not met and the influence 
of the acoustic properties of the reflecting surface is added to the 
characteristics of the microphone. The effect of the diffusion of the 
sound field and the tendency for most materials to be more absorbent 
for sounds of high frequency appears to cause the response under 
studio conditions to be more nearly like that obtained when the 
sound approaches in a direction parallel to the diaphragm and makes 
the departures from the pressure calibration less marked than the 
field calibration for a direction normal to the diaphragm would 
indicate. This perhaps accounts in part at least for the instances 

12 W. C. JONES [J. S. M. P. E. 

in which a corrective network designed to compensate for the field 
calibration normal to the diaphragm failed to effect a material 
improvement in quality. 

The acoustic conditions under which a microphone is used cover 
a wide range. It would therefore be difficult if not impossible to 
adopt a set of conditions for use in connection with a field calibration 
of the condenser microphone, which would be known to be represen- 
tative of those encountered in practice. The pressure method of 
calibration on the other hand is definite, simple, and is capable of 
being accurately duplicated in different laboratories. In view of 
this situation it would seem advisable to retain, at least for the 
present, the thermophone or pressure method of calibration for 
general use. In cases where precise quantitative measurements 
are required a field calibration of the microphone should of course 
be secured under the conditions of actual use. Various methods of 
making such a calibration have been proposed. The Rayleigh disk 
has been used extensively in this work thus far but there are certain 
very definite limitations to the extent to which it can be applied. 
An interesting discussion of the use of the Rayleigh disk may be found 
in papers by E. J. Barnes and W. West, 10 and L. J. Sivian. 11 

It would seem reasonable to expect that future design work would 
be directed toward reducing transition, resonance, and phase differ- 
ence effects to a minimum. The results of work along this line 
have been reported by S. Ballantine 12 and D. A. Oliver. 13 In both 
instances the mechanical design is such that the resonant cavity in 
front of the diaphragm is eliminated and the housing is spherical or 
stream line to reduce the diffraction effect. There has as yet been 
little opportunity to determine the extent of the practical improve- 
ment effected by these changes in design and the whole discussion 
continues to be somewhat academic in character. 

Carbon Microphone. Bell's original microphone was essentially a 
generator and hence was limited in its output to the maximum speech 
power available at its diaphragm. The demand for telephonic 
communication over longer distances led to the early introduction 
of a carbon microphone. In this instrument the resistance of the 
carbon element is caused to vary in response to the sound pressure 
on the diaphragm and produces changes in the current supplied 
from an external source of electrical potential, which are fairly faithful 
copies of the pressure changes which constitute the sound wave. 
The carbon microphone is therefore in general an amplifier in which 


a local source of power is controlled by the acoustic power of the 
sound wave. 

The carbon element or "button" of the first microphones (Edison 
1877) was made from plumbago compressed into cylindrical form. 
This type of button was relatively insensitive and shortly after its 
introduction the suggestion (Runnings 1878) was made that the 
space between the diaphragm and the fixed electrode be "partially 
filled with pulverized engine coke," 14 in order to increase the number 
of contact points and render them more susceptible to the forces 
developed by the motion of the diaphragm. When at its best the 
Runnings transmitter was fairly efficient but at times was erratic 
in its performance due in part to the nature of the microphonic 

FIG. 7. Western Electric Company's 387 type carbon microphone. 

material. In 1886 Edison 15 proposed the use of granules of hard 
coal which had been heat treated. This was an important advance 
for carbon made from anthracite coal is not only used in the micro- 
phones which are being considered in this paper but in commercial 
telephone transmitters as well. 

As in the case of the condenser microphone, the displacement of 
the diaphragm of the carbon microphone must be substantially 
constant at all frequencies if uniform response is to be obtained. 
In the early microphones of the carbon type diaphragm resonance 
introduced rather prominent irregularities in response. Air damped 
stretched diaphragms offered one solution of this problem. During 
the World War instruments of this type were developed and applied 
to the problem of locating airplanes. In 1921 double button stretched 



[J. S. M. P. E. 

diaphragm microphones were made available for use with the public 
address equipment installed for the inaugural address of President 
Harding and the exercises at Arlington on Armistice Day. 16 The 
carbon microphones employed in sound picture recording are of the 
stretched diaphragm double button type. The electrical output 
from this type of microphone is not only of substantially uniform 
intensity over a wide frequency range but due to the "push-pull" 
arrangement of the buttons is comparatively free from harmonics; 
A typical example of the present day carbon microphone is shown 


FIG. 8. Cross-sectional view of the 387 type carbon microphone. 

in the photograph, Fig. 7. Fig. 8 is a cross-sectional view of the 
same type of microphone. 

The diaphragm is made from duralumin 0.0017 inch in thickness 
and is clamped securely at its outer edge. The clamping surfaces 
are corrugated and emery cloth gaskets are provided to prevent 
slipping. The stretching of the diaphragm is done in two steps. 
The initial stretching ring is first advanced by means of six equally 
spaced screws until the diaphragm is smooth and free from irregular- 
ities. The inner or final stretching ring is then adjusted to a position 
which gives the diaphragm a resonant frequency of 5700 cycles per 



second. The method employed in making the determination of the 
resonant frequency is substantially the same as that used in con- 
nection with the assembly of the condenser microphone, with the 
exception that the frequency at which the maximum output occurs 
is usually determined by ear rather than by the coupler method 
previously described. In order to insure a uniformly low contact 
resistance the portions of the diaphragm which are in contact with 
the granular carbon are covered with a film of gold deposited by 
cathode sputtering. 

A spacing washer 0.001 inch in thickness separates the diaphragm 
from the damping plate. A single concentric groove is provided 
in the damping plate. 

The buttons are of the conventional cylindrical type but are pro- 
vided with a novel form of closure to prevent carbon leakage at the 








s s 











_ J 




100 1000 I0.00( 

FIG. 9. 

Pressure calibration of the 387 type carbon microphone. 

point where they make contact with the diaphragm. The closure 
consists of twenty-seven rings of 0.0004 inch paper clamped firmly 
together at the outer edge and spreading apart at the inner edge to 
form a structure which effectively seals the junction between the 
diaphragm and the buttons without adding materially to the mechani- 
cal impedance. 

As has already been pointed out the granular carbon is made 
from selected anthracite coal. The size of the granules is such that 
they will pass through a screen having 60 meshes per inch but will be 
retained on a screen having 80 meshes per inch. Before heat treat- 
ment the raw material is treated with hydrofluoric and hydrochloric 
acids to reduce the ash content. Each button contains 0.060 cc. of 
carbon, i. e., about 3000 granules. 

The bridge which supports the button on the front of the diaphragm 
partially closes the acoustic cavity on that side. It is essential, 

16 W. C. JONES [J. S. M. P. E. 

therefore, that it be so proportioned as to have a minimum reaction 
on the response of the microphone and yet provide the required degree 
of rigidity. It was this consideration that led to the smooth stream 
line contour now employed. 

Referring to Fig. 9 it will be observed that the adoption of an 
air damped stretched duralumin diaphragm for the carbon micro- 
phone has resulted in an instrument having a substantially uniform 
response over a wide range of frequencies. The arrangement of the 

FIG. 10. Apparatus employed in calibrating the 387 type carbon 

apparatus employed in securing the data from which this curve was 
plotted is shown in the photograph Fig. 10. The microphone under 
test was mounted in a highly damped room at a distance of six to 
eight feet from a source of sound which consisted of two loud speaking 
receivers. One of the receivers was the conventional form of moving 
coil direct radiator and was used to provide sound in the lower fre- 
quency range. The other was a special moving coil receiver with a 
short horn so designed as to serve as an efficient source of sound up to 
10,000 cycles. l7 To reduce the effect of standing waves the mounting 



for the receivers was so constructed that they could be rotated through 
a circle approximately five feet in diameter and always face the 
microphone under test. Before starting the test of the carbon micro- 
phone the receivers were calibrated by placing a calibrated condenser 
microphone at the point where the test instrument was to be located 
and determining the receiver current required to produce a pressure 
of one bar (one dyne per square centimeter) on the microphone dia- 
phragm. The condenser microphone was then removed and the 
test microphone substituted. The open circuit voltage developed 
by the microphone when supplied with a direct current of 0.025 


FIG. 11. Circuit employed in calibrating the 387 type carbon microphone. 

ampere per button was then measured. The data obtained in this 
way are essentially a "pressure calibration" of the microphone and in 
interpreting them in terms of "field" performance the same factors 
must be taken into account which have been discussed in considerable 
detail in connection with the condenser microphone. 

The circuit employed in measuring the response of the carbon 
microphone is shown on Fig. 11. Two steps are involved in the cali- 
bration of the sound source. With the output terminals of the micro- 
phone circuit and the sound source short circuited and the polarizing 
voltage for the condenser microphone removed, the attenuator is 

18 W. C. JONES [J. S. M. p. E. 

adjusted until the voltage applied to the measuring circuit is that 
developed by the condenser microphone when a sound pressure of one 
bar is impressed on its diaphragm. A record is made of the reading 
of the output meter in the measuring circuit. The polarizing voltage 
is then applied to the condenser microphone. After the output 
terminals of the attenuator have been short circuited an alternating 
current of a known frequency is supplied to the sound source and 
the magnitude of this current adjusted until the meter reading is 
the same as that previously obtained with the attenuator. This 
completes the calibration of the sound source for that frequency. 
After the carbon microphone has been placed in the position pre- 
viously occupied by the condenser microphone, the polarizing voltage 
is once more removed from the condenser microphone and the output 
from the carbon microphone circuit impressed on the measuring cir- 
cuit. The reading of "the output meter is recorded. The sound 
source and carbon microphone circuit are then short circuited and 
the output from the attenuator again applied to the measuring circuit. 
The attenuator is adjusted until the reading of the output meter 
is the same as was previously obtained with the carbon microphone 
in circuit. In this way the voltage applied to the measuring circuit 
when the carbon microphone is in operation is determined. The 
open circuit voltage developed by the carbon microphone may then be 
computed from the voltage and the constants of the microphone 
circuit. At the locations where these measurements were made a 
certain amount of interference from 60 cycle circuits and low fre- 
quency acoustic disturbances was encountered. The high pass 
filter in the measuring circuit was introduced to facilitate the measure- 
ments under these conditions. The adjustable low pass filter was 
used to confine the measurements to the fundamental frequency. 
Only that portion of the apparatus to the left of the dotted line was 
mounted in the damped room. 

The two buttons of the carbon microphone are identical in their 
dimensions and if the granular carbon is in the same mechanical 
state have substantially the same electrical characteristics. They 
are also practically free from the cyclic variations in resistance known 
as "breathing" which result from the temperature changes caused by 
the power dissipated in the granular carbon. It is, however, a matter 
of every-day experience that a given mass of granular material will 
occupy different volumes depending upon the configuration of the 
particles. In the case of microphone carbon this change in con- 


figuration of the granules results in changes in the contact forces of 
sufficient magnitude to affect the resistance and sensitivity. If these 
changes occur in unequal amounts in the buttons electrical unbalance 
results. When complete balance exists the electrical output is free 
from all harmonics introduced by the circuit. Hence, in using the 
microphone care should be taken to see that a fair degree of balance 
between the buttons is maintained. 

The performance of a carbon microphone may be affected adversely 
by cohering of the granules. Severe cohering is accompanied by a 
serious reduction in resistance and sensitivity which persists for an 
extended period unless the instrument is tapped or agitated mechani- 
cally. One of the common causes of cohering is breaking the circuit 
when current is flowing through the microphone. Experiment has 
shown that the insertion of a simple filter consisting of two 0.02 
m^t. condensers and three coupled retardation coils each having a self- 
inductance 0.0014 henry, will effectively protect the microphone 
button from cohering influences without introducing an appreciable 
transmission loss. This filter may be located in the base of the 
mounting or in a container fastened to the back of the microphone. 

Aging of granular carbon may result from changes in the contact 
surface caused either by mechanical abrasion or overheating due to 
excessive contact potentials. Aging is usually accompanied by an 
increase in resistance and loss in sensitivity. Care should therefore 
be exercised in the use of the carbon microphone that it is not subjected 
to unnecessary vibration which would cause the granules to move 
relative to one another and abrade the surfaces. The use of ab- 
normally high voltages should also be avoided. 

The quality of transmission obtained with the double button carbon 
microphone compares favorably with that secured with a condenser 
microphone. The carbon microphone also requires less amplification. 
There is, however, one characteristic which limits its use, namely, 
carbon noise. The level of the noise is much higher than that due 
to thermal agitation within the carbon granules 18 and appears to be 
caused by heating at the contacts between the granules. A certain 
amount of gas is contained in the pores in the contact surfaces. When 
current passes through the button, a sufficient increase in contact 
temperature takes place to cause a portion of this gas to be driven off 
and produce the non-periodic changes in resistance which give rise 
to carbon noise. 

In conclusion, it may be stated that the condenser and carbon 

20 W. C. JONES [J. S. M. P. E. 

types of microphones have been developed to a point where there 
is little to choose between them from the standpoint of quality of trans- 
mission. The design from a mechanical standpoint has also been 
carried to a point where little difficulty should be experienced in 
their use if reasonable precautions are exercised. Although requiring 
less amplification than the condenser microphone the extent to 
which the carbon microphone is used at present is limited by the 
higher noise level obtained. The condenser type of microphone has 
therefore been adopted for most of the recording work in the sound 
picture field. 


1 DOLBEAR, A. E. : "A New System of Telephony," Scientific American 
(June 18, 1881), p. 388. 

2 LaLumiere Electrique, 1881, p. 286. 

8 WENTE, E. C.: "A Condenser Transmitter as a Uniformly Sensitive In- 
strument for the Absolute Measurement of Sound Intensity," Physical Review, 
(July, 1917), pp. 39-63; "Electrostatic Transmitter," Physical Review (May, 
1922), pp. 498-503. 

4 CRANDALL, I. B.: "Theory of Vibrating Systems and Sound," pp. 28-39. 
Van Nostrand Co 1927. 

5 CRANDALL, I. B.: "The Air Damped Vibratory System: Theoretical Cali- 
bration of the Condenser Transmitter," Physical Review (June, 1918), pp. 449- 

6 ARNOLD, H. D., AND CRANDALL, I. B.: "The Thermophone as a Precision 
Source of Sound," Physical Review (July, 1917), pp. 22-38; WENTE, E. C.: 
"The Thermophone," Physical Review (April, 1922), pp. 333-345; FLETCHER, 
H.: "Speech and Hearing," 1929, Appendix A. 

7 MARTIN, W. H., AND GRAY, C. H. G.: "Master Reference System for Tele- 
phone Transmission," Bell System Technical Journal (July, 1929), pp. 556-559. 

8 ALDRIDGE, A. J.: "The Use of a Wente Condenser Transmitter to Measure 
Sound Pressures in Absolute Terms," P. 0. E. E. Journal (Oct., 1928), pp. 223- 
225; BALLANTINE, S.: "Effect of the Diffraction around the Microphone in 
Sound Measurements," Physical Review (Dec., 1928), pp. 988-992; WEST, W. : 
"Measurements of Sound Pressure on an Obstacle," Inst. Elec. Eng. Journal 
(1929), pp. 1137-1142. 

These curves are taken from unpublished work of P. B. Flanders of the 
Bell Telephone Laboratories, Inc. 

10 BARNES, E. J., AND WEST, W.: "The Calibration and Performance of the 
Rayleigh Disc," Inst. of Elec. Eng. Journal, 65 (1927), pp. 871-880. 

"SiviAN, L. J.: "Rayleigh Disc Method for Measuring Sound Intensities," 
Philosophical Magazine (March, 1928), pp. 615-620. 

11 BALLANTINE, S. "Contributions from the Radio Frequency Laboratories," 
No. 18 (April 15, 1930). 

"OLIVER, D. A.: "An Improved Microphone for Sound Pressure Measure- 
ments," Journal of Scientific Instruments (April, 1930), pp. 113-119. 



14 RHODES, F. L.: "Beginnings of Telephony," (1929), p. 79. 
16 U. S. Patent No. 406,567, 1889. 

16 GREEN, I. W., AND MAXFIELD, J. P.: "Public Address Systems," A. I.E. E. 
Journal (April, 1923), pp. 347-358. 

17 BOSTWICK, L. G.: "An Efficient Loud Speaker at the Higher Audible Fre- 
quencies," Journal of the Acoustical Society (October, 1930), p. 242-250. 

18 JOHNSON, J. B.: "Thermal Agitation of Electricity in Conductors," Physical 
Review (July, 1928), pp. 97-109. 


MR. COOK: I believe it has been stated in some of the published literature 
that the main contribution to the mechanical impedance of the diaphragm from 
the air chamber back of this diaphragm is from an increase in stiffness alone. 
Is the advantage of that thin slice of air in stiffness or is it in resistive load as 
far as the diaphragm alone is concerned? 

MR. JONES: It is true that in the early microphones, such as the Wente micro- 
phone shown in Fig. 2, the air film introduced considerable stiffness as 
well as resistance. In the later designs where an effort has been made to secure 
maximum sensitivity, the stiffness of the air film has been materially reduced 
by the use of a grooved damping plate. The resistance introduced by the air 
film is now the more important factor and in microphones of the type described 
in this paper is relied upon to give the desired degree of flatness of response at 

MR. LEWIN: I should like to inquire, regarding the condenser microphone, 
how constant does the tuning point maintain itself and how often should it be 
checked? In our studio we have a number of microphones which have been in 
use for over two years, and I wonder if it is necessary to re-check the tuning 
point after such a long period. 

MR. JONES: The tuning of a microphone diaphragm involves two factors, 
namely, its effective mass and stiffness. If either or both change a different 
resonant frequency may be obtained. There is no evidence that the diaphragm 
changes its mode of vibration. Inasmuch as it is the predominant mass no 
change in the resonant frequency is introduced from this source. Changes in 
stiffness might arise from slipping at the diaphragm clamping surfaces or a 
drop in tension if the stresses in the diaphragm material are too near the yield 
point. All the available data point to stable clamping and the characteristics 
of the diaphragm material are such that the stresses are well below the yield 

MR. KELLOGG : One wonders on hearing the statement in the paper in regard 
to the large contribution which the air behind the diaphragm makes to the net 
stiffness of the diaphragm, whether the air film might be relied on rather than 
the tension on the diaphragm to give the necessary high natural frequency. 
I assume that the tension must be sufficient to keep the diaphragm flat, but I 
should be interested in what Mr. Jones has to say about this possibility. I 
wonder if it would be asking too much to have the author give further explana- 
tion of the reasons why and the conditions under which the free-space calibra- 
tion seems to give a result which is no more representative of what you actually 
hear than the pressure calibration. 

22 W. C. JONES 

MR. JONES: In regard to the use of air stiffness to secure a high resonant 
frequency, my suggestion is this: It is common knowledge that the stiffness 
of an air film is a function of frequency. The stiffness is small at the low fre- 
quencies where the air is readily displaced when the diaphragm vibrates. At 
the higher frequencies there is a tendency to imprison the air and compress 
it and a higher stiffness results. If air stiffness were relied upon to control the 
resonant frequency, these changes in stiffness with frequency would make it 
difficult to secure uniform response. In addition it should be borne in mind 
that a small separation between the diaphragm and damping plate is necessary 
if the desired degree of sensitivity is to be obtained. A high diaphragm stiff- 
ness is required to maintain this separation. 

Perhaps I did not make my views in regard to the relative merits of the pres- 
sure and field calibrations entirely clear. I didn't mean to convey the impres- 
sion that the pressure calibration is a better measure of what goes on under free 
space conditions. In fact, if quantitative acoustic measurements of high pre- 
cision are to be made with a condenser microphone, it is essential to secure a 
field calibration under the actual conditions of use. The "field" conditions 
which exist in different studios vary to such an extent that it is difficult, if not 
impossible, to arrive at a set of acoustic conditions which are representative of 
all conditions of use. The pressure calibration on the other hand is precise and 
can be duplicated in any laboratory. It would therefore appear advisable to 
retain for the present the pressure calibration for checking and comparing instru- 
ments and make such corrections as are necessary to fit each set of studio con- 



Summary. By means of microphone concentrators high quality sound pickup is 
rendered possible at distances of the order of 20-40 feet. One such device utilizes a 
metal horn with, the microphone placed at the throat. In another form, applied 
commercially by RKO Studios, sound is picked up by an ellipsoidal or parabolic 
reflector and focused on a microphone, with the sensitive face of the transmitter turned 
away from the action. The advantages of this type of concentrator are relatively 
high gain, ability to record against wind or noise interference, and suitable acoustic 
characteristics for high quality pickup at a distance. The importance of these factors 
in lowering moving picture production costs is described. 

When speech is picked up electrically with a microphone it is 
usually possible to secure high quality only by placing the pickup 
device relatively close to the source of sound. It is well known that 
the higher speech frequencies, on which intelligibility largely de- 
pends, are projected from the mouth in a beam. With the pickup 
close to the speaker a considerable portion of the energy in this beam 
is utilized. Moreover, when the microphone is close to the speaker, 
the direct output of sound predominates, whereas with the pickup at 
a greater distance from the source, sound reflected from the walls of 
the enclosure becomes a factor, and the acoustic characteristics of 
the room or stage enter into the equation. The microphone does not 
discriminate, as does, the human ear, between the direct emission of 
speech sounds and the heterogeneous reflections which are set up in 
an acoustic enclosure. 

In talking picture production it is always necessary to compromise 
between the demands of the camera and those of the microphone. 
If the microphone were always placed in the most favorable position 
for sound pickup, it would frequently come within the field of the 
camera. If the microphone is kept outside the camera lines, as is 
required in photographing the action, it may be so far from the source 
of sound that the quality deteriorates. Moreover, the camera has an 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** RKO Radio Pictures, Hollywood, Cal. 


24 CARL DREHER [J. S. M. P. E. 

important advantage in production in that by using proper lenses it is 
often feasible with a given stage set-up to photograph close-up and long 
shots at the same time. The unaided microphone, on the contrary, 
will pick up high quality sound corresponding to the close-up picture 
only when it is near the speaker, say, within three or four feet. Thus 
it is frequently necessary to make additional takes merely in order to 
get correct sound pickup corresponding to the two views. This 
conflict between sound and picture requirements is shown graphically 
in Fig. 1. 

If it were possible to modify a microphone in such a way that high 
quality speech could be picked up at a distance corresponding to a 
medium camera shot, takes for sound only could in many instances be 



FIG. 1. Showing simultaneous photographing of long shot and close-up and 
consequent limitations on high quality sound pickup. 

eliminated, with a resulting saving in time and cost. The procedure 
would then be to shoot close-up sound only, modifying the quality in 
re-recording when necessary to simulate more distant pickup for the 
long shot picture. In the attainment of this objective, promising 
results are being secured by the use of microphone concentrating 
devices. One such development has been described by Olson and 
Wolff. l Substantially this is a metal horn in the shape of a parabola 
of revolution, with the microphone placed at the small end, as shown 
in Fig. 2. At the higher speech frequencies the horn functions as a 
parabolic reflector, focusing sound on the microphone. At a lower 
frequency there is a transition from the reflector action to one in 
which the horn reenforces the lower notes. Peaks of response in this 

Jan., 1931] 



range are smoothed out by the addition of Helmholtz resonators 
coupled to the horn at the throat. The increase in pressure at the 
focus over pressure in free space is of the order of five times. The 
device is directional for frequencies above 200 cycles. The Olson- 
Wolff device is in successful operation at various points in the sound 
picture and radio broadcasting fields. 

Fig. 3 shows another type of microphone sound concentrator 
which is in use at RKO Studios in Hollywood in sound picture pro- 
duction. The microphone is turned away from the source of sound. 
Sound issues from the source, strikes the reflector, and is concentrated 
to a focus, at or near which the microphone is placed, with its dia- 
phragm or sensitive element facing the reflector. Various types of 
reflector curves may be used, such as parabolas and ellipses. In most 


FIG. 2. Horn sound concentrator. 

cases the curve is an open one, corresponding roughly to a parabola of 
the equation y 2 = I2x. The diameter of the surface varies, 40 to 60 
inches, being commercial shapes. Means for sighting and orienting 
the bowl are provided, so that the action may be conveniently 

The technic of picking up sound with such a device is not as 
simple as the theory would indicate. The horn must be kept pointed 
at the source of sound for good quality pickup. With the above 
moderate dimensions the concentrator loses low frequencies (below 
about 500 cycles) to some extent, and contributes a marked increase 
in pressure, corresponding roughly to a stage of amplification, at 
high frequencies. In order to obviate excessive reinforcement of 
higher frequencies it is necessary to modify the shape of the curve or 



[J. S. M. P. E. 

to throw the microphone somewhat out of focus. In general the 
effort is to make the device a soft focus acoustic element, rather than 
to utilize maximum sharpness of focus. While there are certain 
voices which benefit decidedly by the dropping out of the lower tones, 
others become harsh and strident, and care must be used in fitting 
the characteristics of the concentrator to the type of pickup. How- 
ever, with experience it is not difficult to arrive at a proper setting for 
use under average conditions of pickup. 

The directional properties of reflectors of the type described are 
often valuable in discriminating against interfering noises. For 
example, in RKO's Danger Lights it was necessary to shoot some 


FIG. 3. Open-bowl sound concentrator. 

scenes in a railroad roundhouse. With an open microphone it was 
impossible to pick up intelligible dialog at a distance of three feet 
from the speaker, but by utilizing the directional properties of the 
parabolic concentrators, good dialog pickup was possible at much 
greater distances, the noises being reduced to a realistic background. 
Another advantage of the device is in outdoor shooting, when wind 
interference is encountered. When the concentrator can be turned 
with its concave face down-wind, it acts as a shield, the microphone 
being in the lee of the reflector. Wind interference is a frequent 
cause of delay in outdoor shooting, so that this property is valuable 
from a production standpoint. 

Promising experimental results have also been secured with the 

Jan., 1931] 



device indoors. On a properly constructed set it is at times difficult 
to discriminate by ear between the pickup of an open microphone 
three feet from the speaker and concentrator pickup at a distance of 
twenty feet. In general it is advisable to place the concentrators no 
further from the action than the cameras. The concentrator may be 
mounted on a parallel under which a camera is set up. Sets in which 
reverberation is kept down to a minimum are required, since concen- 
trators in sizes which will not interfere with photography have little 
directional effect at the lower frequencies. However, the loss of lows 
in the device may compensate roughly for the tendency toward low 
frequency reverberation commonly found in moving picture sets. 

FIG. 4. 

To date RKO Radio Pictures have used this form of microphone 
concentrator for almost all outdoor pickup in connection with 
such pictures as Danger Lights, Silver Horde, and Cimarron. 
The absence of reverberation outdoors makes it relatively easy to 
apply the device without sacrificing quality. A sizeable increase in 
speed of production and facility in photographing is realized. A 
ten or fifteen per cent reduction in over-all production cost may be 
realized by the skillful use of sound concentrators instead of open 
microphones. Not only is the microphone taken out of the zone of 
action, but by reason of the directional properties of the reflector 



[J. S. M. P. E. 

camera blimps can usually be dispensed with outdoors, thus further 
freeing the cameramen from the limitations imposed by sound. The 
photographs show the RKO concentrators on location (Fig. 4 and 
Fig. 5). 

The horn type of concentrator was developed by Harry F. Olson 
and Irving Wolff of RCA Photophone, Inc., under the supervision of 
Julius Weinberger. Major credit for the open-bowl type of concen- 
trator is due to C. W. Horn, now General Engineer of the National 
Broadcasting Company, who applied it in the broadcast studios of the 

FIG. 5. 

Westinghouse Electric & Manufacturing Company at Pittsburgh as 
early as 1923, and was granted a patent, No. 1,732,722, on October 
22, 1929, the application being dated January 2, 1924. Parabolic 
reflectors were used for airplane location work during the World 
War, but their use for broadcast pickup appears to have originated 
with Mr. Horn. The application to motion picture sound recording 
was carried on by Ralph K. Spotts, Philip J. Faulkner, Jr., and other 
members of the Sound Department of RKO Studios under the direc- 
tion of the writer. 


1 OLSON, HARRY F., AND WOLFF, IRVING: "Sound Concentrators for Micro- 
phones," Journal of the Acoustical Society of America, 1 (April, 1930), No. 3. 



MR. TAYLOR: Wouldn't it add to the interest if we were told one or two spots 
where the reflector was used and why it was desirable at that spot? 

MR. BATSEL: It is my understanding that the reflector was used in all exteriors 
in the entire feature. 

MR. READ: What material was used in the concentrator? A metal? 

MR. BATSEL: I don't know what was used. I know that in experimenting 
they used different materials plasters having various absorption characteristics. 
I believe this one was hard plaster but I am not sure. 

PRESIDENT CRABTREE: Has this method been used in the East? 

MR. BATSEL: The first one shown, the horn type, has been used in the East 
on short subjects and in broadcasting. The larger reflector is a development of 
the West Coast. We have not seen one here as yet. 

MR. KELLOGG: I was told a number of years ago that large parabolic reflectors 
had been tried in broadcasting work and had been discarded. Can anyone tell 
what the faults were? 

MR. KNUDSON: There must be difficulty in getting fidelity for frequencies 
having wave-lengths comparable with the dimensions of the reflector. From the 
photographs it would appear that the reflector is five or six feet in diameter; 
difficulties, therefore, would be introduced at frequencies below about 300 cycles. 

MR. BATSEL: Mr. Dreher has already covered that subject pretty well in his 
paper. He doesn't claim that the device gives equal quality to a 3 foot pickup, 
and the diameter of the reflector is a serious consideration in picking up low 
frequencies. If a small reflector is used, a considerable range of frequencies is lost. 

MR. HILL: I have made forty or fifty measurements on it under a variety 
of conditions and what Dr. Knudson said holds true. The cut-off at the low 
frequency end is serious excepting with reflectors 15 or 16 feet across. There is 
an advantage in that a gain of 10 or 12 db. may be obtained on some frequencies, 
but not at the low frequencies. 

MR. KNUDSON: I should not like these remarks to be construed that we are 
disapproving of the directive microphone. I think the demonstration we have 
listened to today is ample justification for its use. The quality of reproduction 
resulting from the combined use of reflector and microphone was strikingly 
exhibited in Mr. Dreher's demonstration. Listening to the low puffs of the 
locomotive, you are conscious of distortion in the low frequency sounds. The 
high frequency hissing of the steam, I think, was recorded perfectly. The results 
attained were certainly worth while in spite of the limitations of the combined 
use of reflector and microphone. 

CARL DREHER (Communicated) : Mr. Batsel has already answered most of the 
questions. Mr. Read asked what materials were used in the construction of 
the reflector. In some of the early types, we used plaster on burlap and similar 
materials, but in the forms which have been applied commercially, the usual 
material for the reflector has been aluminum sheeting about one thirty-second 
inch thick, backed by wooden cross-pieces to add rigidity. When the reflectors 
are manufactured in quantity, an all-metal form would naturally be adopted, 
but, up to now, the number built at RKO has not justified the manufacture of a 

As pointed out by Dr. Knudson and as I stated in the paper, there is a loss 


of bass with reflectors of commercial diameters (40-60*). This is more pro- 
nounced with the original sharply focused parabolic concentrators used in Danger 
Lights. As was stated in the paper, we have obviated this to some degree by 
using the microphone out of focus and by developing other forms of reflectors, 
notably the ellipsoidal type shown in the photographs. 

Frequency characteristics and measurements do not always give a true indica- 
tion of the commercial value of an acoustic device. Such measurements are of 
the utmost value in indicating methods of improvement and lines of future 
development, but the actual conditions of motion picture recording are so com- 
plex that what appears to be a serious fault in theory may at times be a benefit 
in practice. There are situations in motion picture recording when it is de- 
cidedly beneficial to drop out some of the energy in the lower part of the frequency 

Again, we must consider recording as only one part of the process of making 
a picture, and we must also consider cost. For example, if a given form of pickup 
yielded good acoustic quality and allowed extreme mobility in camera work, we 
might be justified in using that form of recording in preference to another which 
afforded slightly better, sound at a great sacrifice of other picture elements. 
With the reflector concentrators we have been able to make some shots which 
added greatly to the interest of the pictures as a whole, and which would have 
been quite impossible Ajfith the more orthodox methods of pickup. 

Moreover, if we can reduce production costs appreciably by a slight or moderate 
sacrifice of sound quality, there are times when we may be justified in taking 
that course. Many pictures are made with much greater restrictions in casting 
photography, set construction, etc., because of commercial limitations on ex- 
penditures. I do not wish to be understood as advocating deliberate sacrifices 
in quality of sound recording. No engineer would be justified in recording 
poor sound, no matter how cheaply he did it, or how much he facilitated the 
work of the other crafts thereby. My position is merely that, as compromises 
must often be made, devices like the microphone concentrators described in 
the paper may find a very useful field of application and that in the present state 
of the art it is necessary to follow up such developments in the field as well as 
in the laboratory. 


Summary. Inasmuch as the common methods oj measuring motion picture 
screen reflection factors fail to bring out the essential differences between metallic 
and beaded screens, and fail to correctly describe the diffusing screen, a modified 
test procedure is suggested. This involves brightness measurements in two planes 
mutually perpendicular and perpendicular to the screen on which the incident beam 
is inclined at some suitable angle above the screen axis. Such a modification of 
test procedure permits the accurate analysis of a screen in terms of its suitability 
for a particular theater. 

Tests of screen color are also recommended whereby the screen surface color and 
the color of the light source may be brought into closer coordination. 

A superficial examination of the surfaces of a number of motion 
picture screens suggests their division into three classes. A plain 
matte surface such as white plaster gives a screen of an extremely 
diffusing type. A surface prepared with a metallic paint gives a 
surface which provides somewhat less diffusion and more specular 
reflection. Covering the screen surface with fine glass beads gives it 
specular characteristics strikingly different from those of the metallic 
surface screen. Two kinds of tests for the evaluation of quality in 
motion picture screens have been in use up to the present time. The 
first test evaluates the total reflection factor. The second test indi- 
cates the brightness of the screen surface, illuminated at normal 
incidence, when viewed from different angles. 

The customary procedure used at present for testing motion picture 
screens closely follows that described by Mr. L. A. Jones and his 
associates in papers read before the society in 1920 1 and 1927 2 and 
published in the Transactions. In these tests the light was incident 
on the screen perpendicular to the surface and the brightness was 
observed at various angles in the plane perpendicular to the screen 
and passing through the incident beam. It was assumed that for a 
screen to be satisfactory, the ratio of the greatest to the least bright- 
ness should be no greater than 4:1. The greatest brightness would be 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Electrical Testing Laboratories, New York, N. Y. 




[J. S. M. P. E. 










80* 60* 40* 20* 

20* 40* 60* 80* 

Jan., 1931] 



observed on the axis of the screen, that is, at degree; and the least 
brightness would be observed at as great an angle as the width 
of the house permitted. 










_ TO S 



80* 60 40 20* 0* 20* 40* 60* 80* 

In actual practice the incident beam is inclined downward onto the 
screen, making an angle with the horizontal of from 5 to 25, de- 
pending on the design of the house. The need for testing screens at 
such an angle is clearly shown in Figs. 1,2, and 3. The upper curves 



[J. S. M. p. E. 

show screen brightness data with the light incident normally. The 
lower curves show the light incident 12 off the normal. In this case, 
separate determinations must be made in the horizontal and vertical 
planes. These are shown by full and dash lines, respectively. It will 
be noted from these curves that the diffusing screen shows substan- 
tially the same results irrespective of the angle of light incidence, 
whereas the beaded and metallic surface screens appear substantially 
the same when tested at normal incidence, but diametrically opposed 
when the incident light is 12 off the axis. 
















0* 60* 40* 20* 0* 20* 40* 60* 6 




' L 1 


ED 12* 




0* 60* 40* 20* 0* 20* 40* 60* 8 

FIG. 3. 

Another point in which the test at normal incidence fails to show 
the screen as it really is in practice can be seen by comparing the 
maximum brightness of the three screens under the two conditions 
of the test. This is shown in Table I. 

Maximum Screen Brightness 

Screen Normal Incidence 12 off Normal 

Beaded 58 ml. 62 ml. 

Metallic 48 ml. 52 ml. 

Diffusing 14 ml. 14 ml. 

This suggested change in the test procedure makes possible the 
more accurate use of another criterion in the comparison of screens. 

Jan., 1931] 



The fact that one observer in a house might see the screen four times 
as bright as another observer would seem to be of less consequence 
than for one observer to see one edge of the screen two or three times 
as bright as the other edge. For the comparison of screens without 
regard to a particular theater, suitable angles such as 12 or 15 










I 47 





I 12 


I 10 
1. 10 

I 05 
I 05 

I Oo 

I 05 




I 12 

FIG 4 

may be arbitrarily chosen or experience may indicate the advisability 
of making complete tests at two angles, say, 12 and 25. 

The chart, Fig. 4, shows a typical theater in elevation and one- 
half of it in plan, on which are recorded screen brightness ratios 


taken from edge to edge of the screen. In each group, which are 
assumed to be 20 feet apart, the upper number refers to the beaded 
screen, the center number to the metallic screen, and the lower one 
to the diffuse screen. From the viewpoint of axial to marginal 
brightness a person viewing the diffusing screen from one of the back 
corners of the house would see it at its worst. In the case of the 
metallic and beaded screens the variation of brightness over the 
screen from a single observation point becomes of increased im- 
portance. The location which, according to this criterion, presents 
the poorest view for the metallic screen would be that nearest the 
screen in the angle of specular reflection from the lower edge. Assum- 
ing the front row of seats to be at about twice the screen width 
from the screen, an observer sitting in a central front seat would be 
viewing the lower edge at approximately 12 to the normal, the upper 
edge at approximately 35 to the normal and there would be a varia- 
tion in brightness on the metallic screen of about 3 to 1, assuming the 
illuminated field was actually uniform as viewed from the projector. 
The poorest view for the beaded screen, judged by the same criterion, 
would be near the screen and just below the incident beam. In this 
position the observer would see the bottom edge of the screen at ap- 
proximately 12 and the top at about 17 or a variation of screen 
brightness of about 5 to 1. 

Since a change in test procedure is being advocated, it might be we-11 
to consider the advisability of including a test of the variation of re- 
flection factor with wave-length. There are a few tinted screens on 
the market for which special claims are advanced and among the so- 
called "white" screens the degree of whiteness is by no means con- 
stant. Just as the angular brightness tests involve the shape of 
the house, so the spectral brightness tests involve the spectral com- 
position of the projector light source for the complete interpretation 
of results. It is a fact which can be substantiated by test that since 
high intensity arcs, low intensity arcs, and Mazda lamps differ slightly 
in color, screens can be chosen to match any of these particular sources. 

In view of the fact that our present test procedure shows, first, the 
metallic and beaded types of screen to have the same brightness 
characteristics, which is not the case in actual practice, second, that 
the data are not sufficiently complete to make screen brightness com- 
parisons possible from any part of the house, third, that the projection 
angle is practically never at incidence in a motion picture house, 
and fourth, that the importance of color or variations in whiteness 


is at present ignored, it is suggested that the Society review the situa- 
tion with the thought that some modification in test methods might 

be recommended. 

It is a pleasure to acknowledge obligation to E. I. Du Pont de 
Nemours & Company who through the kindness of their Dr. Mc- 
Burnie provided the screens used in getting data for this paper. 


1 JONES, L. A., AND FILLIUS, MILTON F.: "Reflection Characteristics of 
Projection Screens," Trans. Soc. Mot. Pict. Eng., No. 11 (1920), p. 59. 

2 JONES, L. A., AND TUTTLE, CLIFTON: "Reflection Characteristics of Pro- 
jection Screens," Trans. Soc. Mot. Pict. Eng., X, No. 28 (Feb., 1927), p. 183. 


MR. RAVEN: I heartily agree with Mr. Little in his comment that some 
thorough work should be done in this matter with regard to reading screen 
brightnesses from angles and positions that approximate the actual conditions 
in the theater rather than by projecting the light normally and having the 
angle readings taken from that. As Mr. Little has said, little worthwhile 
information can be obtained by a screen purchaser from a reading taken when 
the light is normal. I hope the Projection Committee will take up the matter 
thoroughly so that the exhibitor will soon have available some real information 
that will enable him to decide what screen is best suited for his particular 

MR. TUTTLE: In the paper referred to by Mr. Little, of which Mr. Jones and 
I are the authors, we discussed the effect of varying the angle of incidence. In 
none of the large number of screens which we tested did the magnitude of the 
angle of incidence affect the measured value of reflection factor by any con- 
siderable amount. 

From our experience, I should say that the method of test which we used is 
just as applicable as that advocated by Mr. Little. I am inclined to think that 
the differences between the results of the two methods are not real, but are due 
to misinterpretation of the original data. 

In our data, the value of the zero degree reflection factor should, of course, 
be taken as the factor for regular reflection i. e., angle of incidence equal to 
angle of reflection and the other values given represent factors at various 
angles from the angle of regular reflection. When properly interpreted such 
data are applicable to conditions existing in any theater. 



Summary. Dubbing is essentially a re-recording process and has three important 
applications. The first is the re-recording of a completed feature from one form 
to another, as from film to disk, for release purposes. The second is the re-recording 
of the dialog, for the purpose of mixing in with it, sound effects or incidental music 
which, for technical or economic reasons, could not have been put in during the 
original recording. The third application is the synchronizing of foreign voices 
to a picture which was originally recorded in English. This last is a "doubling" 
rather than a dubbing process. 

The original meaning of the term "dubbing" as applied to sound 
pictures was simply the process of re-recording a sound record. 
The object of re-recording is usually to transform the record from 
one form to another, as from film to disk, or vice versa, or else 
simply re-record in the same form, for the purpose of changing 
the recorded level or frequency characteristic. But with the rapid 
development of sound pictures the meaning of the term "dubbing" 
broadened more and more, until at the present time, it is used rather 
loosely to describe any process whereby the original recording is 
modified in any way. It is also used to describe the process whereby 
foreign versions of domestic pictures are made by synchronizing 
foreign voices to the lip movements of the original version. This 
latter process is essentially a "faking" process, since, when viewing 
such a picture, the voices we hear are not those of the original cast, 
but of an entirely different group of people. The same principle 
was used in some of the earlier domestic talking pictures in an effort 
to maintain the popularity of certain actors and actresses, whose 
speaking accents or singing voices would have been a disappointment 
to the film fans. So-called "voice doubles" were used to actually 
speak or sing while the player himself simply went through the lip 
motions. This form of faking, however, has been completely aban- 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Paramount Publix Corp., Long Island City, N. Y. 


doned now and the public may rest assured that they are actually 
hearing the voices of their favorites, in all domestic releases. 

For the purpose of discussion, dubbing may be classified into 
three broad groups: 

(1) Straight Dubbing 

(2) Combined Dubbing and Synchronizing 

(3) Dialog Dubbing 

To make the discussion complete it might be well to also add a 
fourth group which may be called "indirect recording." This is 
not a form of dubbing at all, but since it is one purpose of this paper 
to dispel the illusion which many people seem to have, that most 
sound pictures are full of artificial and faked effects, it would be well 
to say some words later on this subject also. 


Straight dubbing is the process of re-recording a sound record 
by reconverting the recorded vibrations into electrical vibrations 
and using these reproduced vibrations to make a new record, 
straight dubbing may be subdivided into four groups: 

(1) Film to Disk 

(2) Film to Film 

(3) Disk to Film 

(4) Disk to Disk 

In a studio, such as Paramount's, where all recording is originally 
done on film, film to disk dubbing is the most common form of 
straight dubbing. It is used only on completed features and short 
subjects, after they are ready for release, and is done for the purpose 
of making the product available to houses which are equipped for 
disk reproduction only. 

Straight dubbing from film to film is used only for the purpose 
of level and quality correction. It sometimes is found, when editing 
a film, that various sequences which were recorded at widely sepa- 
rated times, or by different monitor men, or which were subjected 
to different laboratory processings, do not match each other in 
level or quality. In such cases the faulty sequences can be re- 
recorded and the level changed or the quality corrected by the use of 
suitable equalizers. This form of dubbing becomes less and less 
necessary as the personnel of the studio and laboratory become more 
expert in their respective duties, but occasionally instances do arise 
where expensive retakes can be avoided by suitable dubbing from 

40 GEORGE LEWIN [J. S. M. P. E. 

film to film. Level correction is made by simply raising or lowering 
the recording level of the dubbed record to what is considered the 
correct value. The level can be reduced to any desired point without 
difficulty, but in raising the level we are limited by the surface noise 
which is inherent in any form of recording. Quality correction is 
made by inserting suitable equalizers into the dubbing circuit. These 
will be discussed more fully later on. Film to film dubbing has its 
most important application in combined dubbing and synchronizing 
and will be discussed more fully under that heading. 

Disk to film dubbing is comparatively rare ; however, on one or two 
special occasions it has proved quite useful in this studio. Dubbing 
from ordinary pressings is not entirely satisfactory as the surface noise 
is somewhat high. Better results are obtained by dubbing from 
a metal mould, which has been chromium plated for the purpose. 
The surface noise from a chromium plated dis 1 ; is about 6 db. lower 
than that of a regular pressing, for the same signal output, and there 
is also a noticeable improvement in the reproduction of high fre- 

Straight dubbing from disk to film is done for release purposes 
by studios which record originally on disk. One or two special cases 
of disk to film dubbing are worthy of mention. One of these was 
where a certain musical selection which had been recorded on disk 
for the scoring of a feature picture was desired for a new feature on 
film. Rather than go to the expense of bringing in a full orchestra 
to make a new sound track, the selection was dubbed from the disk 
and served the same purpose. Another instance was where a silent 
picture, The Silent Enemy, had been scored entirely on disk. The 
first reel of this picture had a spoken prologue which had been origi- 
nally recorded on film and later dubbed into the disk. On releasing 
this picture for foreign countries the problem was encountered of 
making a new first reel disk which would contain the prologue in the 
language of the respective countries to which it would be released. 
The different languages had already been recorded on film. The 
problem was solved by dubbing the entire first reel from the disk 
onto film. This film was in turn dubbed back to disk and as the 
spoken prologue started, the English version was turned off and the 
foreign version turned on. After the prologue finished we turned 
back to the music and completed the reel. It will be noted that the 
music on the completed first reel was therefore dubbed twice, from 
disk to film and then from film back to disk. 

Jan., 1931] DUBBING 41 

Disk to disk dubbing has practically no application in a studio 
which does all its original work on film. In a studio which records 
on disk, however, this form of dubbing is undoubtedly just as im- 
portant as film to film dubbing in this studio. 


Combined dubbing and synchronizing is by far the most important 
application of the re-recording principle. After a picture has been 
completed and is cut into its final form as regards action and 
dialog, we find that much still remains to be done before it is 
ready for release. We find, for instance, many dialog scenes 
which are supposedly occurring in places where we would expect 
various forms of background noise to be heard. For instance, 
the dialog may be taking place in a street, and we would naturally 
expect to hear the characteristic street noises in the background. 
Actually, of course, such scenes are, as a rule, recorded in the studio, 
without the background noises and it becomes necessary to put these 
sounds in after the picture is complete. This is accomplished by 
combined dubbing and synchronizing. 

The question might be raised as to why such scenes are not recorded 
in their actual location, with the real background noises taking 
place during the actual shooting of the dialog. There are several 
answers to this question. In the first place, there are many locations 
which are often called for in stories, where it would be practically 
impossible to do combined recording and photographing. 

For example, if we were walking along a crowded and noisy street, 
and were at the same time trying to hear the conversation of two 
people walking in back of us, we could probably do so without much 
difficulty, because our ears would automatically concentrate on 
what we were trying to hear and would reject all extraneous noises. 
A microphone, unfortunately is not capable of differentiating between 
what we are trying to record and the background noises, for it will 
pick up the latter with discouraging fidelity. In addition to this 
there is the difficulty of controlling crowds of curious onlookers and 
of placing cables and other sound equipment in locations where traffic 
is heavy. For similar reasons it would not be practical to do any 
recording on an actual train. It would be found that while the 
noise of the wheels striking the rails would seem natural enough 
to a person actually sitting in a train, it would sound all out of pro- 
portion to the dialog when heard in the theater. 

42 GEORGE LEWIN [J. S. M. P. E. 

All such scenes must therefore be recorded in the studio, using 
an artificial set, and any background noises which may be necessary 
are easily put in later by dubbing. They can then be controlled 
and made to sound just as we want them to. Other examples 
of sound effects best put in by dubbing, which are worthy of mention, 
are thunder and wind noise for storm scenes, the roar of cannon or 
gun shots for battle and fight scenes, the noise of passing trains 
and automobiles for indoor scenes where it is desired to convey the 
effect that outdoor noises are being heard. 

The argument might be raised by those who advocate natural 
sound effects as opposed to artificial ones, that, granted it is im- 
possible to successfully record natural sound effects together with 
the dialog in the actual location, we might at least record them in 
the studio while the actual dialog takes place. It should be 
pointed out in this connection that dubbing of all such characteristic 
noises rather than recording them together with the action, has an 
advantage not only as regards tone fidelity, but also from an eco- 
nomic standpoint. It is of great importance that a feature be com- 
pleted in the shortest possible time. If production is delayed while 
the monitor man experiments with the balance between voices and 
sound effects, the cost of production mounts up rapidly. The work- 
ing crew during the shooting of a feature picture usually consists 
of about forty people, and is composed of directors, assistants, sound 
men, cameramen, electricians, and so forth, in addition to the 
players and extras, of whom there may be hundreds during some 
scenes. A dubbing crew for sound effects, on the other hand, con- 
sists at the most of ten or twelve men and they can in one or two 
working days synchronize a complete feature picture. By putting 
in the incidental effects after the picture is completed, considerably 
more time can be devoted and more pains taken to obtain the desired 
effects, at but a fraction of the cost. 

Another important advantage of dubbing in sound effects is that 
stock sound tracks of these effects can be dubbed whenever necessary. 
This studio has a record of a thunder storm which has stood in good 
stead in the dubbing of several pictures. 

Incidental music is almost always dubbed in after the picture is 
completed. In many pictures there are sequences which can be 
rendered more effective by the addition of a background of appro- 
priate music, which can either be played by an orchestra while 
the dialog is being re-recorded, or can be dubbed from previously 

Jan., 1931] DUBBING 43 

recorded sound track. The present tendency is to avoid the use of 
music during the shooting of the picture wherever possible, as the 
presence of music in the sound track hampers the editing of a picture. 
Without music under the dialog it is possible to rearrange se- 
quences, and make additions or omissions wherever desired when 
cutting the picture. This would be impossible, of course, if there were 
music in the track. 

Straight musical sequences, however, such as songs or dance scenes, 
are usually recorded with an orchestra on the set. Attempts have 
been made in the past to economize on the use of orchestras during 
the shooting of such sequences, by having the artist sing or dance 
only to the accompaniment of a piano and drum, and then later 
dub a full orchestral accompaniment over this. This has not 
proved very successful, as it has been found difficult to keep the 
orchestra in exact time with the original track in dubbing, and even 
more important than this, it has been found that the artist usually 
does not perform with as much enthusiasm accompanied by piano 
and drum as he does with the aid of a full orchestra. 


Dialog dubbing is the expression used to describe the synchro- 
nizing of words to the lip movements of a picture which was shot 
silent, or with sound in some other language. This is not really a 
dubbing process at all, as it does not involve the re-recording prin- 
ciple, and is mentioned only for the sake of completeness. Dialog 
dubbing is used principally in adapting domestic pictures for foreign 
release. The foreign market has always been very important in 
motion pictures, from an economic standpoint. In the days of 
silent pictures, there was no particular problem involved, as it was 
only necessary to translate the English titles into the foreign language. 
The advent of sound pictures introduced a new problem, and three 
different solutions have been attempted. One is to record the pic- 
ture in the foreign language while the English version is being made. 
This is done by having two casts, one for each version, and so 
record each scene in both languages. This plan was used in mak- 
ing the French version of The Big Pond. A disadvantage of this 
method is that the success of a picture usually depends upon the 
popularity of its star, and unless he can also appear in the foreign 
version, the picture is considerably handicapped from the box-office 
standpoint. It is also difficult to obtain a full cast in America to 

44 GEORGE LEWIN [J. S. M. P. E. 

speak a foreign language without traces of American accent. The 
second method seeks to overcome this problem by making the foreign 
version in the foreign country itself. This method is quite expensive, 
however, and the finished product still lacks the box-office attraction 
of the original star. 

The third method is the so-called "dubbed" version. In this 
method the original picture is preserved, but a foreign cast is as- 
sembled and after much painstaking preparation, a foreign dialog 
script is prepared which matches the lip movements of the original 
version. This script is then recorded in synchronism with the original 
picture. The dubbed version has the advantage of preserving the 
original cast in the picture, but is very difficult to synchronize, 
and there are many places where it is undoubtedly apparent that 
the voices have been faked. 

In making the dubbed version, only the dialog is recorded. 
After this has been completed, the picture must be scored and syn- 
chronized, just as an original version is. If several foreign versions 
of the same picture are to be made, as is often the case, it is a good 
plan to record all synchronized music and sound effects on a separate 
track. All the foreign versions can then be synchronized by dubbing 
this sound track. 


We come now to a short discussion of the technical problems in- 
volved in dubbing. An ordinary recording channel is used, and the 
output of a projection machine is fed into one of the mixer positions on 
the monitor table. In the case of straight dubbing, this is all that 
is necessary, except for the addition of suitable equalizers, if they are 
required. In the case of combined dubbing and synchronizing, 
several projection machines or sound dubbing heads are fed into as 
many mixer positions, in order to combine several sound tracks. At 
the same time microphones and non-synchronous records can also be 
mixed in. In some elaborate cases of combined dubbing and syn- 
chronizing, as many as seven or eight mixer positions may be in use 
simultaneously. These might include the original dialog, a sound 
track of street noises, a synchronized track of background music, 
a non-synchronous record of characteristic crowd noise, one or two 
microphones for direct pickup of special sound effects, and so forth. 
All of these are under control of the monitor man and can be faded 
in or out in any desired combination. The combined output is 

Jan., 1931] DUBBING 45 

recorded in the usual fashion on film to produce a new negative 
which is finally cut into the finished picture. 

Obviously, the quality of the combined product depends to a great 
degree upon the fidelity with which each separate sound track is 
reproduced during the dubbing process. There is a certain amount 
of distortion inherent in any form of reproducing apparatus. In a 
high-grade projector using a carefully prepared release print this 
distortion is quite small, and for this reason the sound reproduction 
in high-class theaters is as a rule quite satisfactory. When re- 
producing sound track for dubbing purposes, however, it should be 
remembered that whatever distortion is present, even though it be 
very slight, it is recorded into the new sound track, and when this 
track is again reproduced in the theater, the two distortions add up, 
and the final effect is much more noticeable. 

It might be well at this point to go into some detail regarding the 
inherent distortion present in a sound projection machine so as to 
make clear why it is negligible in a theater using high-quality release 
prints, and why it constitutes a serious problem in dubbing work, 
where we must obtain exceptionally good reproduction and must 
get it from green film. (Green film is the name given to film which 
is fresh from the laboratory and has not been run through a pro- 
jector more than once or twice.) The distortion present in a sound 
projector may be divided into two types. One is the loss of high 
frequencies, and the second is the introduction of a mechanical 
nutter due to lack of absolutely uniform motion of the film past the 
scanning beam in the sound gate, which results in distortion of the 
high frequencies. The simple loss of these high frequencies is not a 
very serious matter in a good projector. By actual measurement of 
frequency test films, recorded at constant level with our best com- 
mercial recording set-up, there is no appreciable loss up to 2000 
cycles, and from this point upward, the loss increases gradually 
to about 9 db. at 6000 cycles. This loss includes both the recording 
and reproducing loss, and is not serious because it can be compensated 
for by the use of a suitable equalizer. 

The introduction of mechanical flutter, however, is a much more 
serious problem. This flutter is apparently caused chiefly by the 
friction which is present between the film itself and the pressure 
pad which holds it in the focal plane of the optical system of the 
sound head. If the film has become thoroughly dry and the emulsion 
hardened by several days' aging, and if it has acquired a slight 


coating of oil as a result of having been played through a projector 
five or six times, the friction between film and pressure pad is very 
slight and uniform, and the flutter is quite negligible. If, on the 
other hand, the film is green, the friction is much greater and less 
uniform, with the result that considerable flutter is produced which 
results in reproduction which is popularly described as being fuzzy 
or raspy. In addition to this, the softness of the emulsion allows 
some of it to scrape off and pile up on the pressure pad to such an 
extent that the film sometimes goes considerably out of focus, with 
resulting loss of volume especially at the high frequencies. 

Much work has been done on the development of special equipment 
which would be capable of high quality reproduction regardless of 
the mechanical condition of the film. An ordinary film recording 
machine has recently been modified to enable it to be used as a 
reproducer, and appears to solve the problem quite well. This 
machine is capable of reproducing up to 9000 cycles without ap- 
preciable flutter, and the frequency characteristic is better than 
that of an ordinary projector to the extent of about 6 db. at 6000 
cycles, without equalization of any sort. Another development 
which has been worked out for the purpose of accelerating the dub- 
bing and synchronizing of pictures, is a "toe recording" process 
which enables one to dub directly from the negative of a sound 
track, without waiting for a print to be made. Toe recording 
is the process whereby the exposure in recording is held down to a 
point where we operate on the toe of the negative H & D curve of 
the film, rather than on the straight line portion. This process 
has been evolved with the view of making the negative and print 
interchangeable, so that prints can be made if desired, but the nega- 
tive itself can be used to save time. As a matter of fact it has been 
found that the negative gives even better quality than a regular 
process print. Use of this process is made in cases where the syn- 
chronizing music is first recorded on separate tracks and these tracks 
later dubbed with the original dialog. 


In recording sound tracks which are to be used for dubbing pur- 
poses, the level is kept as high as possible, so that the ground noise 
will be relatively low. This is important especially when equalizers 
are used, as the action of an equalizer usually results in bringing up 
the ground noise. Two forms of simple equalizers are used. In 

Jan., 1931] DUBBING 47 

dubbing from film to wax it is, of course, necessary to reduce the 
energy of the low frequencies ; this is done by shunting an inductance 
coil of proper value across the projector output. In this way there is 
obtained a gradual cut-off of low frequencies from 500 cycles down. 
In dubbing from film to film use is made of a tuned circuit filter 
giving a gradual rise at high frequencies beginning at about 2000 
cycles and coming to a peak at 6000 cycles. This rise in high fre- 
quencies approximately compensates for the combined loss which 
takes place in recording and reproduction. 


As is quite well known, it is important to have the microphone 
reasonably close to the source of sound in order to obtain a good 
recording. Instances often arise where extremely long shots are 
necessary and make it impossible to get the microphone closer to the 
principals than thirty or forty feet. A good example of a case of 
this sort is in the shooting of large chorus scenes with one or two 
principals singing out in front. In viewing such a picture the 
audience would naturally expect the voices of the soloists to be clear 
and distinct, and to stand out from the voices of the chorus, and yet 
it would obviously be impossible to get a microphone close to the 
soloists and at the same time keep it out of the camera angle, es- 
pecially if the principals move back and forth during the rendition 
of the number. In instances such as these we resort to what is known 
as "indirect recording" or more popularly, the "synchronous play- 
back." In this method the sound is recorded first, without the 
picture, so that the singers may be placed in any way desired. After 
a good take is obtained, it is printed and then played back on the 
stage through large horns. The cast then take up their regular 
formation on the stage and go through their actions in synchronism 
with the sound coming from the horns, while the cameras grind. The 
picture is then printed together with the original sound track, and 
the final effect gives the illusion that both sound and action took 
place at the same time. In this way it is seen that full scope is give 
to both the sound men and cameramen to do the most justice to 
their respective tasks without handicapping each other. It should 
be understood, however, that this is not a faking process in the or- 
dinary sense of the word, because the voices we hear are actually 
those of the people we see, except that they were not recorded at the 
same time that the action was photographed. It cannot be called a 


dubbing process either, since the original sound track is used. It is 
mentioned in this paper simply for the sake of completeness in order 
to cover all forms of recording other than simple, direct recording. 

In closing this paper I would like to emphasize the fact that or- 
dinary dubbing is not a form of faking, since, regardless of how many 
times a voice may be re-recorded for the purpose of adding sound 
effects, it still remains the actual voice of the person who is seen 
speaking in the picture. The only time voices are really faked is in 
the preparation of foreign versions in which case it is done only to 
bring to foreign countries at least the face and personality, if not 
the actual voice, of a popular star. The old practice of using "voice 
doubles" to fake the speech of actors whose own voices were not 
suited for recording has been completely abandoned, and only those 
players who can record as well as act have survived the complete 
transformation which the microphone has wrought in the motion 
picture industry. 


Summary. It is suggested that the most promising line of development of the 
three-color camera will involve use of three films sensitized primarily for light of dif- 
ferent colors, and that a lens of 50 mm. focus and f/2 speed will be used in connection 
with twin revolving bladed mirrors for splitting the light from the lens. The require- 
ment of the positive print will be met by means of a transparent dye mordant that 
will at least retain the size and outlines of the negative grain to produce the necessary 

It seemed to the writers that a general outline of the problems con- 
fronting those engaged in trying to improve three color subtractive 
pictures might be of interest to the members of the Society. 

Up to the present only two color subtractive pictures have been 
shown, and while great improvements have been made in two color 
subtractive cinematography, these pictures only seem to stress more 
greatly the need for a three-color process. It is apparent that color 
cinematography will never be generally demanded by the public until 
it can portray colors with a reasonable degree of accuracy. 

The problem is divided into two parts: first, the design of the 
camera, and second, the chemistry and the development of the 
mechanisms necessary to produce a three-color film adapted for use in 
any theater without changes in the projection apparatus. 

It is generally conceded that any practical color camera must make 
its color separations simultaneously to avoid intolerable flashes or 
fringes of color around moving objects and that all three separations 
must be made from the same viewpoint; otherwise, it would be im- 
possible to register or superimpose the several component color images 
in the positive. 

Accepting the limitations of a camera for making simultaneous 
separations from the same viewpoint, the next step is to inquire into 
the requirements of lenses with regard to focal length and speed. 
Under sound studio conditions where tungsten light is very largely in 

* Presented at the Fall Meeting, October, 1930, New York, N. Y. 
** Brewster Color Film Corp., Newark, N. J. 



use, and where an excessive amount of light cannot be used on account 
of the incident heat and strain on the actor's eyes, it is necessary to 
use the fastest possible lens having good color correction. The limit- 
ing aperture at the present time is//2. 

The great size of some of the sets used in the studios, and the limited 
floor space of sound stages, make it essential that the color camera be 
adapted to use a wide angle lens of not over 50 mm. focus, though 
40 mm. would be still better. At the same time the beam splitting 
system must permit the use of lenses of from 100 mm. to 150 mm. 
focal length for making simultaneous close-ups and semi-close-ups in 
connection with a 50 mm. camera shooting long shots. 

This is a very difficult requirement for both the 50 mm. and 150 
mm. lenses for several reasons. In a 50 mm. camera it is very difficult 
to get a double beam splitter (adapted to reflect two images and 
transmit one) in the small lengths of 33 or 35 mm. between the rear 
vertex of the lens and the focal plane; while in the case of the 150 
mm. f/2 lens the cone of light leaving the rear vertex is nearly 75 mm. 
in diameter, which very greatly increases the size of the beam splitter 
if no light is to be lost. 

Where two or three matched lenses are used, it is necessary to have 
a beam splitter in front of these lenses to reflect the light rays re- 
ceived from one point into the separate lenses, and where one lens is 
employed the splitter must be behind to divide the light rays pro- 
jected from the single lens into three groups. We believe this can be 
done only in two ways ; either by a series of glass prisms, or by means 
of a highly polished mirror revolving at an angle to the lens and in the 
path of light rays. This mirror consists of a disk having a number of 
slots in it so that one portion of the light rays is transmitted through 
these slots or openings, and after passing through a suitable filter, 
is recorded as one of the separations; the portion of the light rays 
which strikes the polished surface of the blades is reflected through 
another filter to form the second separation; a second mirror revolv- 
ing at right angles to the first is used for making the third separation. 
The mirror usually has three blades and makes at least two revolu- 
tions for each exposure so that each frame is exposed three or four 
times. These repeated exposures have proven to give exactly the 
same effect on the screen as simultaneous exposure of the different 
color separations. 1 

1 U. S. Patent No. 1,752,477. 


The glass prism system has the advantage of extending, in effect, 
the extremely important distance between the rear vertex of the lens 
and the focal plane in proportion to the index of refraction of the 
glass used. It also has the advantage of cheapness when compared 
with the revolving mirrors, while the size of the driving mechanism 
of the camera is reduced thereby preventing noise and reducing the 
size of the camera. 

The revolving mirror system has the advantage of not having to 
transmit the light through glass, which results in a loss of light, but 
what is more important, a possible loss of definition near the edges of 
the picture if the glass path is too long. Most important of all, it is 
possible with a revolving mirror system to make three color separa- 
tions on three separate films from a 50 mm. f/2 lens, without adding 
any lenses to the standard objective to increase the light path be- 
tween the rear vertex and the focal plane. 

The decision as to whether to use one, two, or three films for re- 
cording the color separations depends not only on the camera design, 
but also on the study of the relative efficiency of panchromatic film ex- 
posed through three filters in comparison with that of two or three 
separate films sensitized for the region in the spectrum which they 
are to record. 

Color separations are usually made on panchromatic emulsions by 
photographing through the Wratten filter No. 25 for the red, No. 57A 
or 58 for the green, and 49A, 49, and 49B for the blue. Transmission 
curves for these filters taken from the Eastman filter chart and 
illustrated in Fig. 1 show that No. 25 is nearly an ideal filter for the 
red. It transmits light of its own color, red, with high efficiency and 
then cuts off the other colors abruptly. None of the green filters are 
nearly as perfect they transmit blue-green and green fairly well, 
but cut well into the orange by a long slope, with a possible average 
efficiency in the very important yellow green region of 30% or 40%. 
This critical region which largely controls the true color rendering of 
flesh and foliage is also harmed by the low sensitivity of panchromatic 
film at this point. 

The blue filters 49A, 49, and 49B are even less efficient; their total 
over-all efficiency being only 0.7%, 0.5%, and 0.3%, respectively, and 
of their most favorable colors they transmit only 42%, 26%, and 15%. 
They cut off practically all exposure in the violet and record solely in 

Ithe true blue region, while the sloping cut transmits some of the blue- 
green which should not be recorded by the blue separation. 



The lack of efficiency of these filters is due to inherent qualities 
common to all dyes of these colors and cannot be improved. In fact, 
we have found Wratten filters to be of very high efficiency, and were 
it possible to have filters in the blue and green as good as the red No. 
25, which hypothetical filters are represented by the dotted lines, they 
would be satisfactory. 

By using three separate films for the color separation, it is possible 
to use an old type of non-color sensitive negative for the blue separa- 
tion. The sensitiveness of this type of emulsion stops almost exactly at 


z. -^ fc ^ 

UJ ^ O Ul O 


>, BLUE GREEN.O, GREEN ,> > , 



420 440 460 480 500 520 540 5<30 580 600 620 640 660 680 70O 

FIG. 1. 

the ideal point, naturally recording the violet as well as all of the blue. 
Not having to use a filter, its speed is many times greater than if it 
were necessary to use an inefficient type of blue filter with panchro- 
matic film. Advantage can be taken of this fact by reflecting only a 
small portion (possibly 10% to 15%) of the light rays received from 
the lens to form the blue separation. 

In case of the green separation, the use of separately sensitized 
films is even more important, for we then are able to obtain an 
emulsion which records the green and yellow-green very evenly, 

Jan., 1931] 



almost to the D line, and then abruptly cuts off. Of course this 
emulsion is sensitive to blue, but this blue is cut off by the use of a 
filter of high efficiency such as an Eastman K2. By this means we 
get a much higher over-all efficiency and are able to record the 
yellow-green region with much greater fidelity. 

The red separation can be made on a red sensitive emulsion, but 
the present panchromatic emulsion is excellent for this purpose. 
In either case it is necessary to use the No. 25 filter which cuts in 
exactly the correct place and which has a very high efficiency. 












/ / 





















\ i 


\ B 

1 \ c l 




1 \ 






440 460 480 500 5'zc' 540 560 5$ 


FIG. 2. 

JO 6od 6EO 640 ^80 680 7i 


There is a second point in favor of separate films. It is well known 
that if different portions of a negative emulsion are exposed to light of 
different colors, they will develop to different contrasts for the same 
time in the developer; or these different portions of the films acted 
upon by lights of different colors will have different gammas. This 
would result in an incorrect contrast scale of the color positive, and 
make it difficult, if not impossible, to get a true rendering of high- 
lights and shades; though it would be perfectly possible to reproduce 



middle tones in the picture substantially correctly. The film exposed 
to the red light will develop the highest contrast or gamma, and the 
blue the lowest, for a given time in the developer. For example, if 
the middle tones were correct one might have red highlights and blue 
deep shadows. 

By determining in advance the gamma curves of the separate films 
for light of the three primary colors, it is possible to time the develop- 
ment of these films so that they will produce three negatives of equal 
















1 ^ 































FIG. 3. 

gamma, or contrast range, from which correct positive prints can 
be made. 

In our opinion, the requirements in the positive for each of the 
component images of a three color film are: definition, transparency, 
gradation, and hue. 

Definition, especially for the blue-green and magenta images, is a 
matter of extreme importance. In our experience, it is necessary to 
retain the outlines and size of the negative image grain on the screen 
in order to maintain proper sharpness. Anything less than this pro- 

Jan., 1931] 



duces a soft effect which, although very desirable for certain effects, 
is objectionable for long shots. 

Transparency throughout the entire color range is absolutely es- 
sential. Three color cinematography requires the exact blending of 
all colors, and frequently needs a small percentage of one primary 
mixed with the other two to obtain the exact shade. It is essential 
that each of these primaries, whether in heavy or light shades, shall 
be absolutely transparent and not have the heavy tones blocked up 


3 70 









^ 60 
z 40 
85 30 


B / 






/ j 













440 460 480 500 520 540 560 580 600 620 640 660 680 700 
FIG. 4. 

by a residual silver or mordanted image. The ideal component image 
would be like a color filter, pure color imbedded in the gelatin. 

Finally we come to the hue and gradation of the color images. 
We again have the same difficulty in securing dyes that approximate 
the ideal as noted in the case of the filters. 

The ideal requirements of the three color dyes are that each should 
transmit as nearly as possible 100% of the light of two of the three 
primary colors and in its heavier densities absorb entirely light of the 
other primary color. 


In Fig. 2 Curve C shows the transmission of a heavy step in a 
magenta "H & D" strip and curves A and B the lighter steps. This 
dye passes nearly all the blue and red but no green. Figs. 3 and 4 
show the blue-green and yellow curves for the same densities. 

In order to obtain a good black it is necessary that each of the three 
colors absorb practically all light of one of the other primaries, and it 
is equally important that each in their lighter gradations pass prac- 
tically equal quantities of the corresponding primary in order to 
obtain good greys, as is seen by the opening of the filter in the lighter 
steps. With the three dyes shown equal densities of the three super- 
imposed yield a grey. 


Summary. A motion picture image with green shadows and blue halftones can 
be prepared by toning the image blue in the usual toning solution, fixing in hypo, 
washing, and then re-toning followed by immersion in a solution of a basic dye. 
In this way the first toning bath converts the silver image to a mixture of Prussian 
blue and silver ferrocyanide, the reaction going to completion in the halftones but 
incompletely in the shadows so that some of the silver is unaffected. The silver 
ferrocyanide is removed in the hypo solution leaving an image consisting of pure 
Prussian blue in the halftones and a mixture of this substance and silver in the shad- 
ows. On re-immersion in the blue toning bath, the silver in the shadows is again 
converted to a mixture of Prussian blue and silver ferrocyanide which latter substance 
is a mordant for basic dyes, so that on immersion in a dye solution the dye is absorbed 
only to the shadows. 

Commencing with a black and white image on positive motion 
picture film, it is possible to color this differentially by purely chemi- 
cal means so that the hue of the shadows is different from that of the 
halftones while the highlights remain perfectly clear. 

One method of accomplishing this worked out by one of the authors 
and described previously 1 consists in toning the positive image in 
the usual single solution iron toning bath from which the potassium 
alum has been omitted, washing, and then immersing in a solution 
of a basic dye. The omission of the potassium alum from the for- 
mula causes the bath to convert the halftones to white silver ferro- 
cyanide while only the shadows are toned blue. On immersing the 
film in a basic dye, the halftones assume the color of the dye while 
the color of the shadows is a combination of blue and that of the 
dye employed. For example, safranine gives pink halftones and 
purple shadows while auramine gives yellow halftones and green 

A new method of double toning recently devised produces blue 
halftones and differently colored shadows. The procedure consists 
of four operations as follows : 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Communication No. 455 from the Kodak Research Laboratories. 



(1) Tone the positive print of normal quality in the following: 

Avoirdupois Metric 

Ammonium persulfate 3 1 /* ounces 100 grams 

Ferric alum (ferric ammonium sulfate) 8 x / 4 ounces 250 grams 

Oxalic acid I 1 A pounds 600 grams 

Potassium ferricyanide 8 l /< ounces 250 grams 

Ammonium alum 1 pound 10 ounces 800 grams 

Hydrochloric acid (10%) 6 1 /* ounces 200 cc. 

Water to make 50 gallons 200 liters 

The method of compounding this bath is very important. Each 
of the solid chemicals should be dissolved separately in a small 
quantity of warm water, the solutions allowed to cool, filtered into 
the tank strictly in the order given, and the whole diluted to the 
required volume. If these instructions are followed, the bath will 
be a pale yellow color and perfectly clear. 

Time of Toning Tone fully at 70F. (21C.). The color of the 
toned image varies from a light bluish gray for short time toning 
(about 3 minutes) to a deep blue for long time toning (10 minutes). 

Time of Washing. Wash for 10 to 15 minutes until the high- 
lights are clear. A very slight permanent yellow coloration of the 
clear gelatin will usually occur, but should be only just perceptible. 
If the highlights are stained blue, then either the film was fogged 
during development or the bath was not compounded correctly. 
Washing should not be carried out for too long a period, especially 
with water inclined to be alkaline, because the toned image is soluble 
in alkali. 

Life of Bath. If the acid is renewed to the extent of the original 
amount after toning each 5000 feet, the bath is capable of toning 
15,000 feet per 50 gallons of solution. 

If even after revival the tone remains flat, the bath is exhausted 
and should be thrown away. 

After continued use, a slight bluish sludge will collect in the bath, 
but this is not harmful. Should this form, to any appreciable extent, 
it is a result of incorrect mixing, the action of light, contact with 
metallic surfaces, or the presence of hypo in the bath. 

(2) Immerse in a 10 per cent solution of hypo for 2 to 3 minutes 
and wash for 5 to 1 minutes. 

(3) Re-immerse in the above iron toning bath for 5 minutes 
and wash for 10 to 15 minutes. 

(4) Immerse in the solution of the basic dye for 5 to 15 minutes 

Jan., 1931] DOUBLE TONING 59 

until the desired depth of color in the halftones is obtained. The 
formula for the dye solution is as follows : 

Dye 3.2 grams 

Acetic acid (glacial) 2 cc. 
Water to make 4 liters 

Dissolve the dye thoroughly in hot water, filter, add the acid, and dilute with 
cold water. After toning, wash the film in water until the highlights are clear 
or the halftones are blue. 

Suitable dyes are Safranine A (pink), Chrysoidine 3R (yellowish 
brown) , and Auramine (yellow) supplied by the National Aniline & 
Chemical Company, New York, N. Y. They produce purple, dark 
green, and green shadows, respectively. 

Theory of Process. (a) The iron toning bath consists essentially 
of a solution of ferric ferricyanide in oxalic acid. This reacts with 
the silver image forming silver ferrocyanide and ferric ferrocyanide 
according to the following equation : 

4Fe 3 (FeCN 6 ) 3 + 12Ag = 3Ag 4 FeCN 6 + 3Fe 4 (FeCN 6 ) 3 
Ferric Silver Silver Ferric Ferrocyanide 

Ferricyanide Ferrocyanide (Prussian blue) 

The reaction goes to completion in the highlights but not in the 
shadows so that after toning the composition of the shadows and 
halftones may be represented as follows: 

Halftones Silver Ferrocyanide + Prussian blue 
Shadows Silver + silver ferrocyanide + Prussian blue 

(b) Treatment with hypo removes the silver ferrocyanide from 
the halftones and shadows leaving Prussian blue in the halftones 
and a mixture of silver and Prussian blue in the shadows. 

(c) Further treatment in the blue toning bath does not affect 
the halftones but the silver in the shadows is converted to a mixture 
of silver ferrocyanide and Prussian blue as explained above. The 
composition of the shadows and halftones is now as follows: 

Halftones Prussian blue 

Shadows Silver Ferrocyanide + Prussian blue 

(d) Silver ferrocyanide is a mordant for basic dyes and on im- 
mersion in the dye bath the blue color of the shadows is therefore 
modified by virtue of the addition of the dye. 


Effect of Toning on Sound Track. Tests with both the variable 
area and variable density types of sound records indicated that 
toning by the above method had little or no effect on sound quality. 
It is therefore possible to apply this method to sound prints. 

Equipment. Suitable materials for the construction of processing 
apparatus have been described. 2 Allegheny metal is fairly resistant 
to toning baths but hard rubber is the most satisfactory material 
for constructing sprockets or moving parts which come into contact 
with the toning solution. 


1 "Toning and Tinting of Eastman Positive Motion Picture Film," pub- 
lished by Eastman Kodak Co., Rochester, New York. 

2 CRABTREE, J. I., MATTHEWS, G. E., AND Ross, J. F.: "Materials for the 
Construction of Photographic Processing Apparatus," published by the Eastman 
Kodak Company, Rochester, New York. 


MR. TEITEL: I would like to point out, in regard to multi-toning, that these 
colors have been successfully produced in the laboratories of the Multicolor 
Improving Co., Inc., as far back as 1914. When projected, the colors will 
show up properly only when the subjects portrayed are still objects. If the sub- 
ject were in motion, as a moving person, vehicle or fast moving clouds, the 
effect would be that of a mass of uneven color spots, quite unpleasant to view. 

MR. CRABTREE: I agree, of course. The applications of the process are 



Summary. The arc length-arc voltage relations of the high intensity arc depend 
very largely upon the relative positions of the positive and negative carbons. There 
is a very definite point at which the light is a maximum and the point of maximum 
light is not the point of maximum steadiness. 

It has been shown 1>2>3>4 that the relative positions of the positive 
and negative carbons in the high intensity arc affect its behavior. 
This paper deals with the variations in the relative positions possible 
in commercial lamps where the angle formed by the axes of the two 
carbons is fixed. It will be shown that rather minor variations 
have an unexpectedly large effect on the amount of light and the 
steadiness of the arc. 

The results of these variations are common to all types of high 
intensity lamps and carbons but the greater part of the work de- 
scribed here was done on 13.6 mm. positives with 3 /sin. copper coated 
cored negative carbons at 120 amperes unless otherwise specified. 
The angle of the axes of the carbons was 45 degrees. 

It has been the practice for carbon manufacturers to specify the 
current at which high intensity carbons of various sizes should be 
burned, but they have been reluctant to specify the voltage. A 
glance at Fig. 1 will explain the reason for this reticence. This 
figure gives graphic representations of three 70 volt arcs, but the 
arc lengths, measured as shown in the figure, vary from l l / 6 in. to 
6 /s in. In X the negative flame does not touch the lower part of 
the positive carbon, in Y it just touches it, and in Z it overlaps it 
considerably. These arcs give entirely different results in quantity 
and quality of crater light and the projectionist would only be con- 
fused by any voltage specification without qualification as to the 
relative position of positive and negative carbon and this latter 
relationship is probably more important than the arc voltage. 

*Presented at the Fall 1930 Meeting, New York, N. Y. 

*Research Laboratories, National Carbon Company, Inc., Cleveland, Ohio. 




[J. S. M. P. E. 

The most practical means of studying the results of the movement 
of the positive carbon with respect to the negative is to hold the 
negative carbon tip in one position and move the positive carbon 
along its axis. Graphic representations of the arcs obtained at 120 
amperes by moving the positive carbon successive steps of l /* in. 
along its axis are given in Fig. 2. The arc voltage for this particular 
set varies from 86 in position A to 55 volts in position F. The 
negative flame in position A in Fig. 2 is considerably ahead of the 
positive so that the positive flame actually rolls out of the bottom 
of the positive crater before the negative flame strikes it and diverts 
it upward. As the positive carbon is moved ahead this condition 
is altered so that at D the edge of the negative flame just touches the 
lower edge of the positive carbon and practically the whole negative 


FIG. 1. 

flame is sweeping across the crater opening as though compressing 
the positive flame. Finally at F a good portion of the negative 
flame plays against the bottom of the positive carbon and again 
only a part sweeps across the positive crater. The values of relative 
light and arc voltage for these different arcs at 120 amperes are shown 
in Fig. 3. The maximum useful light is obtained at position D 
(as would be expected from the above description of the action of the 
negative flame against the positive crater opening). The light 
diminishes as the positive is moved in either direction from posi- 
tion D. 

Unfortunately the position of maximum light is not the position 
of maximum steadiness. With the arc in position A, the direction 
of the positive flame from the crater is not stable, resulting in many 

Jan., 1931] 



large flickers in the crater or useful light. This condition is im- 
proved as the positive carbon is moved forward so that the large 
flickers decrease and are practically eliminated at positions C and D. 
In these positions small flickers of rather short duration are evident. 
The negative flame is either just hitting or just clearing the lower 
side of the positive carbon in these positions and tends to oscillate 
on and off the edge of the positive shell in a rapid movement causing 
mediiun size flickers of short duration. 

When the positive has been advanced to position E in Fig. 2 the 
edge of the negative flame is permanently on the bottom side of the 

FIG. 2. 

positive shell and the negative flame drives against the positive arc 
stream with a steady force of uniform direction and magnitude so 
that there is practically no flicker in the useful light from the arc. 
With the arc in this position, a high intensity spot lamp has been 
observed for half an hour at a time without detecting any noticeable 
flicker in the spot. 

The light is lower as shown in, Fig. 3 for this position than in 
position D where some flickering is obtained. The light is still lower 
in position F without any change in steadiness so that the optimum 
condition position is that in which the edge of the negative flame 



[J. S. M. P. E. 

impinges on the positive carbon as close to the end as possible without 
noticeable flickering on the screen or in the spotlight. 

If the positive carbon is changed from C or D to that of E without 
changing the position of the negative or the ballast resistance, as 
is often done in the projection booth, there might actually be an in- 
crease in light with the elimination of practically all of the noticeable 












|_ g 





-1 ft 

ft Q 











8 b 

e> 7 















3 < 

; i 

) E 

; F 

FIG. 3. 

flicker. If the positive is moved in the opposite direction toward 
position A the decrease of light will be much greater than that shown 
in the solid line of Fig. 3. This change is shown by the dotted line 
in Fig. 3 for a 115 volt power line. The reason for this is obvious 
when the decrease of voltage in going from A to F is noted. If the 
ballast resistance and line voltage were kept constant, a movement 


of the positive from position A to any of the other positions would 
necessarily give an increase in current. 

The distance from the projected axis of the positive carbon to 
the tip of the negative carbon for the arc illustrated in Fig. 2 is 
6 /s in. Similar experiments were made with distances of Y 2 in. and 
3 /4 in., with exactly the same results. Within these limits and with 
the same relative position of the positive and negative flames the arc 
length had no noticeable effect on the useful light. 

In the high intensity arc burning 16 mm. positives and 11 mm. plain 
cored negatives with an angle of 28 degrees between the carbon axes, 
it was found similarly that the position of maximum light was not 
that of maximum steadiness and that the edge of the negative flame 
definitely bathed the lower edge of the positive carbon when the 
light was most free from flickers. 


1 JOY AND DOWNES: "Characteristics of High Intensity Arcs." /. Soc. 
Mot. Pict. Eng., XTV (March, 1930), No. 3. 

2 BENFORD: "The High Intensity Arc," Trans. Soc. Mot. Pict. Eng., No. 24 
(March, 1926). 

3 BASSETT: "The High Power Arc in Motion Pictures," Trans. Soc. Mot. 
Pict. Eng., No. 11 (1920). 

4 BASSETT: "Electrochemistry of the High Intensity Arc," Trans. Amer. 
Electrochem. Soc., 44 (1923). 


MR. BASSETT: I should like to congratulate Mr. Downes on this short paper 
with a lot of meat in it because it is the first time that one of the mysteries of 
the high intensity arc has been brought down to a concise explanation. Some 
operators can always get the best out of a high intensity arc, and this was con- 
sidered a special knack. Any operator who will study this paper can acquire 
the knack and improve his projection. 

MR. BENFORD: I think there is one point about that paper that might be 
stressed a little more and that is that it is not always wise to increase the current 
in order to get more light. When the electrode is over-loaded it is likely to 
smoke and the gas becomes extremely unstable. I have known of several cases 
where there is an actual decrease in light after the current had been increased 
some 10 per cent over its rated value. 

PRESIDENT CRABTREE: What are the probabilities of our getting a light 
source of greater brightness ; also what is the temperature of the brightest source 
that you have been able to obtain as compared with the sun? 

MR. BENFORD: The temperature of the high intensity current as measured 
by its color is some 5600 K., a brightness temperature which is comparable 
with that of the sun. 

PRESIDENT CRABTREE: This is of importance in connection with large screen 


pictures. With the present 35 mm. film with a very small aperture, we cannot 
get enough light through it to give a large screen having sufficient brightness. 
That is one of the unfortunate limitations of the use of 35 mm. film for the very 
large theaters. 

MR. DOWNES: In the paper we presented last year, I think at Toronto, there 
were values given for the average intrinsic brilliancy of several high intensity 
arcs. The most efficient one is the 13.6 mm. arc at about 125 amperes when 
looked at from the point of view of high average intrinsic brilliancy. That par- 
ticular one, as I remember it, is of the order of 820 candle-power per square 
millimeter of crater opening area. That is the highest of all the ordinary high 
intensity arcs. The super high intensity arc at about 250 amperes has a higher 
intrinsic brilliancy, say from 850 to 1200 candle-power per square millimeter 
with the sun at about 900. Attempts have been made to use this arc for motion 
picture projection but so far this seems impracticable as this arc tends to be un- 
stable and is very difficult to handle. There is work going on in our laboratories 
in efforts to improve the figures, and we hope that we may be able to get some- 
thing satisfactory for the large size pictures. 

PRESIDENT CRABTREE: Yes, but what percentage increase of brightness over 
the present source are you hopeful of getting? 

MR. DOWNES: To increase the intrinsic brilliancy and at the same time retain 
the necessary steadiness of operation is very difficult and efforts to do both have 
not been very successful so far. Probably slightly larger light sources of about 
the same intrinsic brilliancy as the present arcs can be used. 



Summary. In this paper the 16 mm. home talkie situation is considered from 
the viewpoint of the amateur. The nature and interests of present users of 16 mm. 
apparatus are discussed. It is concluded that only a modest distribution of sound 
equipment among the amateurs will be realized, and that widespread use of this 
equipment will be found in a new group looking more for a source of entertainment 
than for a hobby. Available 16 mm. sound apparatus and subject matter are de- 
scribed. An estimate of possible developments in apparatus and appropriate sub- 
jects is given. There is also a discussion of the amateur's requirements in regard to 
sound apparatus from the technical viewpoint. 

In approaching the problem of the 16 mm. home talkie, it will be 
the purpose of this paper to examine the subject primarily from the 
viewpoint of the users and prospective users of home talkie equip- 
ment, considering its many angles chiefly as the consumer sees them 
and touching upon the questions of its nature, design, production, 
and distribution as they affect or will affect this great potential 
market. The conclusions reached are based on the data which it was 
possible to secure from the industry and upon personal contact or 
correspondence with the thousands of present home movie users who 
are members of the Amateur Cinema League, their international 
organization, or readers of its publication, Movie Makers. 

Prior to the comparatively recent widespread adoption of sound 
motion pictures in the commercial theaters, the home, or amateur 
movie field, was concerned solely with the making or projection of 
silent pictures. It is a major fact in the situation that this is still 
practically the case. One reason for this lies in the difference between 
the interest of those who have so far embraced amateur movies, 
approximately 200,000 people, and the millions who are the patrons 
of commercial movie theaters. Both are seeking entertainment, of 

* Presented at the Fall 1930 Meeting, New York, N. Y. 

** Editor of Movie Makers, magazine of the Amateur Cinema League, Inc. 
t Technical Editor of Movie Makers and Technical Consultant of the Amateur 
Cinema League, Inc. 



course, but the latter find satisfaction in entertainment in which 
they take no part, and of which they are merely spectators. The 
amateur movie enthusiasts, on the other hand, find in their avocation, 
entertainment of an active nature, a recreation in which they are 
producers, exhibitors, and spectators combined. All of these func- 
tions are a present actuality with the silent film, whereas the making 
of home talkies is at present attended with such difficulties that the 
results are nearly always of an indifferent sort. Consequently only 
a part of the enjoyment of home movies to which they are accustomed 
is provided by the present home talkie. One may rent or buy pro- 
fessional 16 mm. talkie productions synchronized with disk records for 
showing on any one of several machines now available for this pur- 
pose. One may be an exhibitor and spectator but not be a producer. 
This, with the vast majority of the present group of amateurs, would 
not seem to be wholly satisfying. Hence, we find a very practical 
psychological reason for the modest distribution to date of sound 
apparatus among the present home movie consumers. 

But, it might be asked, are there not thousands of amateurs who 
are interested only in projection, who have bought projectors in order 
to be able to have their own home movie shows and who are not 
interested in making their own films? Undoubtedly there are some 
who answer to this description, but the limited number would be 
astonishing to anyone examining the situation unless one were more or 
less acquainted with the nature of the home movie enthusiast. While 
it may be obvious that there are practically no camera owners who 
do not have projectors, the converse is also true, that there are very 
few projector owners who do not also own cameras. That more 
projectors are sold than cameras might point to a different conclusion 
but examination of the facts shows that this disparity comes chiefly 
from the wide purchase of projectors by industry for use in selling, 
by schools for the development of visual education programs, and 
so forth. 

Therefore, it would seem reasonable that we may not look to the 
present type of amateur for a wide adoption of home talkies until such 
time as the amateur can make his own. There will be a steady con- 
version of large numbers of the present group, of course, since the 
distinctions which have been drawn are purely relative and vary in 
intensity with the individual. The availability of synchronized 
films, on both a sale and rental basis, is a vital factor. At present, 
the home talkie offerings are distinctly limited, for the combined sale 

Jan., 1931] 


price of film and disk is considerable. Rental libraries for inexpensive 
distribution are just coming into being but undoubtedly these fa- 
cilities will rapidly be improved and an increasing amount of talkie 
equipment be gradually absorbed by a certain percentage of the 
present silent film users. 

But, if this would not seem to promise a wide growth for home talkie 
exhibition, wherein lies the future of this development? Having 
described the present home movie user as somewhat similar to the 
radio fan, who in the early 
days of radio was chiefly con- 
cerned with the making of 
things, we must not forget 
that these radio set construc- 
tors were decidedly limited in 
number when compared with 
the millions who today enjoy 
commercially built radio re- 
ceivers. Nor should we over- 
look the similarity between 
this latter group, enjoying the 
sedentary amusement of radio 
reception, and the millions, 
possibly the very same, who 
patronize the commercial 

That the users of home 
talkies should ever approach 
in number those enjoying radio 
reception seems doubtful. 
While the first cost does not 
seem to be prohibitive, as 

home talkie equipment can even today be bought as moderately as 
a good radio and will undoubtedly be cheaper in the future, upkeep, 
however, is a different matter. The program for a radio set costs its 
owner nothing, at least directly, while home talkie programs mean a 
regular and not inconsiderable outlay. Furthermore, the radio 
requires only the turn of a knob in order to operate it, while the 
showing of a film and synchronized record requires more effort and 
intelligence. However, this problem, which will be discussed more 
fully later on, is not insurmountable. 

FIG. 1. Victor Animatophone with 
unique vertical turntable for 16 mm. 

70 J. B. CARRIGAN AND R. C. HOLSLAG [J. S. M. p. E. 

Let us now consider the 16 mm. talkie equipment commercially 
available. As mentioned before, only projection equipment has to 
date been marketed and all of these machines have provided only for 
sound-on-disk. No sound-on-film apparatus has yet been offered 
commercially, although many companies are said to be working on 
such equipment. Several of the sound-on-disk machines first ad- 
vertised for the home have been withdrawn by their makers because 
of technical obstacles encountered in their satisfactory operation 
under home conditions. At the moment, there are three 16 mm. units 
being offered specifically for home use, the Cine- Voice, produced by 
the Hollywood Film Enterprises, Inc., of Hollywood, California, the 
Tone-O-Graph, manufactured by the North American Sound Pic- 

FIG. 2. Cine-Voice, attachable with flexible shaft to any make of 
16 mm. projector. 

tures Corporation of New York City, and the Filmophone-radio, of 
the Bell & Howell Company of Chicago. Path Films, Inc., is also 
offering a 9.5 mm. machine. Two other units are being distributed 
specifically for use in industry and education, although they may be 
used in the home as well. They are the Project-O-Phone, manu- 
factured by the Bell & Howell Company of Chicago, and the Cinetone 
of the QRS-DeVry Corporation, also of Chicago. Two other units 
which will be appropriate for home use will shortly be announced for 
distribution. They are the Animatophone of the Victor Animato- 
graph Corporation of Davenport, Iowa, and the Visionola of the 
Visionola Manufacturing Company, New York City. 

The Cine- Voice may be attached to any of the 16 mm. projectors 
now in use. It is a separate twelve or sixteen inch turntable unit 


which is operated by the projector motor through a flexible shaft 
attachment. It will play either 33 Vs rpm. theater records or 
78 rpm. home phonograph records. When using the former, a film 
speed of 24 frames per second must of course be used, the regular 
sixteen frames per second for the latter. It can be played either 
through the home radio set or through a standard amplifier and 
dynamic loud sp>eaker which are available as a separate unit. It sells 
from $105 to $129 plus $80 for the amplifying unit. 

The Tone-O-Graph, consisting of motor, projector, and turntable 
for 16 inch records, is a compact unit incorporated in a single carrying 

FIG. 3. Pathe cabinet model for 9.5 mm. sound pictures. 

case. The separate motor unit drives both projector and turntable 
in synchronism. It can be operated through the home radio or a 
separate amplifier unit. It can be adapted for either 33 Ys or 78 
rpm., and film speed of either 24 or 16 frames per second. Its price 
is $175.00, amplification system extra. 

The Pathe" 9.5 mm. machine is cabinet housed and one motor 
operates both turntable and projector. The cabinet may be closed 
during projection, a port being provided in one of the doors for the 
light ray. It sells at $195, plus amplification system. 

The Bell & Howell Project-O-Phone is provided in three carrying 
cases, one for projector, one for dynamic speaker, and one for a turn- 

72 J. B. CARRIGAN AND R. C. HOLSLAG [J. S. M. p. E. 

table and amplifier. The turntable is operated by an induction 
motor independently of the projector motor, excepting in so far as they 
are connected by a flexible shaft, insuring synchronous motor action 
but relieving the projector motor of the turntable load. Its 16 inch 
turntable revolves at 33 Vs rpm., with film speed at 24 frames per 
second. It weighs sixty-nine pounds and sells complete at $761. 

The Filmophone-radio, also manufactured by this company, is a 
combination home talkie and radio placed in a handsome cabinet with 
synchronized turntable for either 78 or 33 Vs rpm. 

The QRS-DeVry Cinetone uses an independent synchronous motor 
which controls both projector and turntable. A specially designed 
governor insures fixed operating speed. Projector, motor, sixteen 
inch turntable, and pickup are contained in one case, the amplifier 
and speaker are packed in another, being separated when in use. 
It operates at 33 L /3 rpm., film speed of 24 frames per second, weighs 
ninety pounds, and is priced at $500 plus tubes. 

The Animatophone is unique in construction, varying from the 
other units described in that the turntable operates in a vertical 
position, perpendicular to the projector base, instead of in the cus- 
tomary horizontal plane. In this instrument, the shaft of the turn- 
table is intimately connected with the projector mechanism, being 
operated through an extension of one of the projector gear shafts, 
thus eliminating the necessity for auxiliary flexible shafts or gear 
trains. The customary electrical pickup and arm are used, counter- 
balanced so that the needle comes in contact with the vertical record 
with the correct pressure for reproduction. It runs either at 33 Vs 
rpm., film speed of 24 frames per second or, by shifting the turntable 
to a secondary geared shaft, at 78 rpm., film speed of 16 frames per 
second. Thus either 16 inch records or ordinary home phonograph 
records may be reproduced. A special "air vane" governor has been 
incorporated in a revised model of the Victor Projector which must 
be used in connection with this unit. The blast from a cooling fan on 
this governor, impinging against a vane which causes a break in the 
circuit when the speed is too high momentarily slows down the motor 
to the proper speed, whereupon the contact is reestablished. Ampli- 
fication may be provided either by the home radio or by means of a 
unit and speaker provided separately. The device will sell at ap- 
proximately $100, not including projector, amplifier, and speaker. 

The Visionola will be the most elaborate unit yet offered, com- 
bining an electric phonograph, projector, radio, and screen, all in a 

Jan., 1931] 



cabinet of the more elaborate console type. The screen is con- 
structed on the underside of the cabinet cover. When raised it 
assumes the proper angle to receive the screen image. A small 
mirror, carried on a collapsible arm drawn from the front of the 
cabinet, reflects the film image from the projector back to the screen. 
A unique arrangement of the film feed and takeup reels on a panel 
in the front of the cabinet allows easy threading. The radio unit is 
placed below the projector unit. The turntable, operated by the 
same motor which operates the projector, is in the upper part of the 

FIG. 4. Bell & Howell Filmophone radio, a 16 mm. talkie 
cabinet model. 

cabinet above the projector. It can be operated at 33 Vs or 78 rpm. 
with appropriate film speeds. This unit will retail at $500.00. 

These, then, are the chief instruments at present available. Films 
synchronized with disks are now being offered in limited numbers by 
various companies, including Bell & Howell, Hollywood Film Enter- 
prises, Q.R.S.-DeVry, Fowler Studios, and, most recently, Pathe". 
Among the present professional producing companies which are re- 
leasing theater sound subjects on 16 mm. through the companies 
mentioned are Ufa, Amkino, Educational Pictures, Inc., and Pathe. 

But what other developments may be looked for in the near future 

74 J. B. CARRIGAN AND R. C. HOLSLAG [J. S. M. p. E. 

on equipment for sound-on-disk picture projection? What does the 
future hold for sound-on-film projection apparatus? Is there any 
prospect of taking-apparatus either for sound-on-disk or sound-on- 
film ? What steps are being taken to provide a larger and finer supply 
of sound film subjects? 

There will certainly be several more sound-on-disk projection 
machines offered in the near future. In the field of amateur record- 
ing, 16 mm. sound-on-disk recording cameras will probably be avail- 
able in 1931. Sound-on-film projection machines will come still 
later, possibly in 1931. Almost certainly the last development will 
be 16 mm. sound-on-film recording cameras. 

In regard to increased offerings of sound films, within six months 
or a year, there should be greatly increased facilities for home talkie 
programs of the highest quality, provided from the professional 
production field. 

Let us now consider some of the practical problems arising in the 
use of home sound pictures by the amateur and some of the advan- 
tages and disadvantages of both sound-on-disk and the sound-on-film 
methods. We have seen from the general development of non- 
professional, or home projection, apparatus that the sound-on-disk 
synchronizer has so far led the field. The reasons for this are logical. 
First of all, the turntable and pickup furnished with the home talking 
picture unit are similar in operation to that of the familiar phonograph 
and usually little difficulty is experienced in making it work properly. 
For the rest, since the turntable is connected to the projector by 
mechanical means, it is only necessary to thread and operate the 
projector in the usual way. The only added points of difficulty, 
therefore, are the careful starting of the pickup needle at an indicated 
spot on the record groove and the placing of a marked film frame in 
the projector gate, a simplified facsimile of the professional procedure 
in a theater projection booth when synchronized records are em- 
ployed. But, whereas the machine in the theater booth is provided 
with specially built pickup and amplifier systems, the electrical and 
acoustical characteristics of pickup, amplifier, loudspeakers, and horns 
being carefully coordinated, the home projectionist usually turns to 
an unclassified selection of electrical apparatus in order to reproduce 
the sound vibrations recorded on the disk. The pickup is always 
furnished with the sound attachment but there is no guarantee that 
good results in amplification will be obtained when the pickup output 
is amplified and reproduced through a radio receiver. Such amplify- 


ing systems are notorious for their widely varying characteristics and 
it is only by chance that the best results are obtained, since the im- 
pedance of the pickup should be taken into consideration when 
designing amplifier transformers for use in conjunction with it. 
Loud speakers also are of widely varying types although in most 
modern sets some form of the dynamic cone is employed. 

The home sound projectionist usually makes no effort to place his 
loud speaker in such a position relative to the screen that the illusion 
of sound actually emanating from the picture is produced. He is 
usually content to leave his loud speaker in a fixed position with rela- 
tion to the radio set many times the loud speaker is incorporated in 
the set and to erect his screen on a wall or table. The sound volume 
simply fills the room, with no directional effect whatever. 

The deplorable tendency to judge a radio set by the amount of 
noise it will emit seems unfortunately to be carried over by the 
amateur to his motion picture sound projection. No matter what 
the size of the screen picture, and it is sometimes as small as 30 by 40 
inches, the tendency is to produce a great volume of sound, simply 
because the amplifier will permit it. Not realizing that this does 
more to destroy the illusion than to create it, this type of amateur 
soon tires of home talkies and wonders why they seem unnatural. 

In general, therefore, it would seem that with the present home 
sound synchronizing equipment now in use, there is little chance of 
even approaching the almost perfect illusion afforded by the specially 
coordinated apparatus used in the better theaters. Until home talkie 
outfits are commercially introduced that are entirely self-contained 
turntable, projector, pickup, amplifier, and loud speaker self-contained 
and technically coordinated the satisfactory reproduction of home 
talkies is uncertain. 

It appears also, that it will be practically impossible to duplicate 
the perfection of theater installations even on a miniature scale, since 
remodeling of rooms to improve acoustical properties, the installation 
of large exponential horns, control boards, and other aids are out of 
the question for the amateur. In most homes, the motion picture 
projector is regarded as a piece of portable equipment to be packed up 
and stowed away in the closet when not in use, and, although several 
manufacturers have introduced the permanent cabinet idea the use 
of a projector as a piece of furniture it has not met with as much 
success as predictions would indicate. One reason probably is the 
already crowded condition of the living room of the average American 


home which boasts its console or cabinet radio set and overstuffed 
furniture. The introduction of another cabinet to take up floor-space 
is frowned upon, and the fact that a talking motion picture cabinet 
with self-contained screen must of necessity be large is a definite factor 
for its sales resistance except in those cases where the home is large. 

Refinements in the mechanics of home talking picture apparatus 
have in a general way followed the early development of professional 
synchronized disk work. Independent designers found that a direct 
connection of turntable to projector without the intervention of 
adequate mechanical filters was unsatisfactory for the reasons that 
the tendency to "flutter" was produced by the projector gears and that 
the projector usually had no electrical or mechanical governor for 
maintaining a uniform speed a requirement absolutely necessary to 
prevent a periodic variation of the pitch of the reproduced sound. 

Many of the familiar professional objections to the sound-on-disk 
system have also been advanced by the advocates of other systems. 
Sound film libraries must store, classify, and combine two commodi- 
ties, the film and the disk. Amateur users must do the same. If the 
film should become torn, synchronism between film and record would 
be destroyed. Black leader or blank film would then have to be 
spliced in, carefully, frame for frame. The proper disk may become 
separated from the film and misplaced. These and a number of other 
objections give rise to the question, "Why not sound-on-film for the 

The problem, of course, is not easy. Lacking definite experience 
with such apparatus for the amateur, it might be appropriate to 
discuss the difficulties that will have to be overcome to make the 
apparatus desirable. 

In the first place, expense would have to be considered. That 
such an apparatus would be costly, there is little doubt. In order to 
secure results better than mediocre, the 16 mm. or amateur sound 
head would have to be as well designed as that of the professional 
projector. Film speed would have to be just as carefully governed 
and regulated in the small projector as in the large one. Yet the 
price of the apparatus would have to be on an amateur basis, not a 
professional one, if such apparatus is to be other than an extreme 
luxury. Other difficulties are mechanical ones. The width of the 
customary 35 mm. sound track, 0.1 inch or 2.5 mm., would have to be 
reduced considerably half this width or less to be accommodated 
in the present picture area of the 16 mm. film and still preserve an 



image of satisfactory dimensions for home projection. Various 
plans have been proposed to overcome this difficulty. One of these is 
to omit the perforations from one edge of the film, leaving this band 
for the sound track. A film moving mechanism can be designed to 
function satisfactorily in this way. However, this location of the 
sound track is such that it would be subject to the extra wear imposed 
on the outer edges of the film. Plans have also been proposed for film 
wider than 16 mm. DeForest has recently announced sound-on-film 
plans involving 20 mm. film. Split 35 mm. film, giving a 17.5 mm. 
width, is also being tried out. These variations from the accepted 
home standard might be practical if controlled by a firm of exceptional 
resources, otherwise they would require the complete redesigning 
and reequipment of the market for this size. Such a step would 
involve so many difficulties, considering the present foothold of 16 
mm. in the home, that a very drastic series of changes would have to 
be instituted to accommodate it. 

Another potential difficulty lies in the fact that speed of 16 mm. 
film in passing through the projector is but 38 feet per minute (even 
at the rate of 24 frames per second), whereas practically all previous 
sound recording has been done at a film speed of 90 feet per minute. 
The problem of recording the higher frequencies at a speed almost 
one-third that of standard practice is a very definite one. 

Even if the recording is done on the standard sound track and 
reduced to small film proportions by optical printing, the compressing 
of the high frequency record into a smaller space may be prevented by 
difficulties in resolution caused by the greater magnification of emul- 
sion "grain." 

It is said, however, that these problems may be and are being over- 
come. If this is the case, there remains but one problem peculiar to 
amateur use. That is the care and operation of the sound-on-film 
device. Such systems involve light-sensitive cells and exciter lamps 
which, with their attendant electrical adjustments, are extremely 
sensitive. Such apparatus attached to the open type of amateur 
projector would in all probability be constantly subjected to abuse by 
a variety of amateur operators who are not particularly trained in 
such use. A home sound-on-film system would therefore have to be 
simplified to the utmost in the matter of control and would have to be 
carefully housed and protected. 

So far, no steps have been taken to provide the amateur with 
means for recording sound. From the number of inquiries received 


through the technical service department of the Amateur Cinema 
League, it is evident that the amateur requires such equipment, so 
that it will be possible to make an audible record with the same ease 
and refinement as a visual one can be made. However, sound 
recording is an unfamiliar subject, even in its simplest form, full of 
technical difficulties. At this juncture, therefore, it may be better 
that the amateur is not provided with apparatus that will record 

Most proposals for sound-on-disk synchronized recording for the 
amateur have involved the engraving of a soft aluminum disk, from 
which a play-back may be obtained immediately by means of a pickup 
actuated by a fiber or cactus needle. A record so engraved and re- 
produced will last for repeated playings and is quite satisfactory as 
far as reproduction qualities are concerned if properly amplified. 
Unsynchronized sound pickup has generally been accomplished 
through the agency of a carbon microphone and amplifier. Record- 
ings have been made at 78 rpm. with much success, although the 
problem of recording at a slower 33 Vs still demands mechanical re- 
finements in most cases. However, these are already beginning to 
appear, so that an entire 400 foot reel may be synchronized on a 16 
inch aluminum disk. 

A number of central sources for the recording of sound have been 
instituted for meeting the slowly increasing amateur demand. To a 
small, properly equipped, sound studio, the amateur may bring his 
films, which have already been developed, have them run off on a 
synchronized projector, and have his sound recorded to match on the 
spot. Such a procedure is entirely feasible and will undoubtedly 
become more prominent in the amateur field as sound reproduction 
becomes more familiar. 


MR. ENGSTROM: From the amateur's standpoint in making his own sound 
picture, what priced apparatus would he be most interested in, what degree of 
apparatus complication would be acceptable, and what standards of sound 
quality would he set up? 

MR. CARRIGAN: The answer to the first question is that the amateur, being 
familiar with the present equipment prices, would be willing to pay not exceeding 
$250.00; generally, he would pay that but would hesitate to pay more except 
in the case of wealthy individuals. It would have to be as simple as possible. 
There are three types of amateurs: the one who knows nothing, the one who 
knows something, and the one who knows a lot. The first and second groups 
form the great majority and would want something very simple. 


With regard to the quality of reproduction, the amateur would not be overly 
critical; he is not so of his film at present. Since he made the picture, he will 
swallow a good deal, and the same would be true of sound. 

PRESIDENT CRABTREE: On the one hand, the amateur has his radio playing 
every day, and occasionally the sound movie; doesn't he have a measure there? 
Except for recordings of himself and his friends, he would probably be just as 
critical as he is of the radio. 

MR. CARRIGAN: I think you are correct; I was thinking of personally made 
films. , - 

MR. TOWNSEND: As I remember, it was mentioned that acoustics in the 
home would need to be corrected. I don't think that is a strong factor. The 
paper also stated that air column horns were necessary. It seems to me that 
the acoustics in the average home are so far ahead of those in the average theater 
that this would not be a difficulty. The average speaker used in the home 
should be acceptable for reproduction of sound pictures. 

MR. CARRIGAN: I was going more deeply into possible refinements. In order 
to get perfection, precautions would probably have to be taken. 

MR. COOK: What size picture would the amateur expect? How long will he 
tolerate this "breadboard" collection of apparatus, or how long will his family 
tolerate it? This is a question that interests the manufacturer. The question 
of price which was brought up by Mr. Engstrom applies to the cabinet machine. 
In cruder for a manufacturer to go into it, he must make a profit. Expensive 
apparatus can be sold, I suppose, but most people won't buy it. The radio and 
automobile industry offer good proof of this. If a manufacturer can market 
this apparatus at a price comparable to present-day prices in radio, he can expect 
a profitable market from those whose earnings are from $1500 to $2500 a year. 

MR. CARRIGAN: I think there the measuring stick will be the radio. I think 
the cabinet outfits could be put forward as cars are. The price will determine 
the size of the market. At first it will probably be a luxury at a high price. 
However, I think a firm could put out a line varying in price and touch various 

The normal size of picture is about 30 by 40 unless it is Kodacolor. I think 
the majority would accept a smaller picture if the screen were incorporated, as 
in the "Visionola," which gives a good effect, and has a smaller screen. 



N. Y. 

PRESIDENT CRABTREE: In order to give everyone an opportunity 
to air his views on the possible methods of securing a large screen 
picture, we reserved a place on this program for an open discussion 
on the subject. As Professor Hardy pointed out, if the photographic 
emulsion were absolutely grainless, if it were sufficiently fast, if it 
were so hard that it could not be scratched, and that it would not 
accumulate dirt, then wide film would not be necessary. Enough 
light could then pass through the film to ensure a reasonably large 
screen picture. 

It has been suggested that the 35 mm. film should be run sideways. 
I think Mr Fear was originally responsible for that suggestion. 
Please correct me if I am wrong. 

MR. FEAR: I believe I was the first. 

PRESIDENT CRABTREE: The wide image has been squeezed opti- 
cally on the 35 mm. film and then stretched out optically in pro- 
jection. You can see an example of that at the Capitol Theater 
this week. This picture was produced by reducing an image on 
70 mm. film down to 35 mm. film. It has been suggested that the 
sound be put on a separate film so as to permit of more picture space 
on the 35 mm. film, and there is the suggestion of the Standards 
Committee to introduce a film intermediate in size between 70 mm. 
and 35 mm. There are probably other alternatives. I should 
like to have your opinions. 

MR. STERN: I gave a demonstration at the Paramount Theater on 
the 30th of September in which standard 35 mm. film was projected 
with the theater's own Magnoscope projector on the large screen 
measuring 43 X 31V2 ft. with excellent definition, and without excess 
granulation. This result was made possible by a special laboratory 
process of my own which will make feasible the use of large screens 
with 35 mm. film. I have also an invention for putting the sound 
track on separate film, saving the whole field for the picture. This 


invention consists of printing two sound tracks on 35 mm. film running 
in opposite directions. The film so printed is processed in the usual 
way and then slit in half, each half accompanying a reel of picture. 
It is wound on a special combination reel, of which one side carries 
the picture and the other side the sound track. 

MR. Ross: We strongly believe in maintaining standards when- 
ever possible. We further believe it would be a mistake to adopt 
a standard of 50 or 65 mm. film or any size other than 35 and 70 
mm. The small house does not have a large enough stage to accommo- 
date wide screen pictures, whereas the de luxe houses have such 
stages. The de luxe house with its comparatively larger box-office 
receipts can easily afford to install 70 mm. apparatus, whereas the 
cost of such a change would be prohibitive to the small house. We 
recommend the use of 70 mm. film and apparatus for the de luxe houses 
and 35 mm. film and apparatus for the smaller houses. Furthermore, 
we believe that sound will eventually be recorded on a separate film. 
The sound for Hell's Angels is produced on separate film having two 
sound tracks. We will have more to say of this during the discussion 
of the question of sound on separate film. It is our belief that all 
pictures should be recorded on 70 mm. film; however, we see no 
reason why pictures dealing exclusively with intermediate and close- 
up shots should not be recorded on 35 mm. film and optically con- 
densed laterally for printing wide film 1 to 1.8 release prints. Mr. 
Fear has modestly refrained from mentioning his system wherein 
the pictures are recorded longitudinally on 35 mm. film, whereby 
70 mm. pictures may be printed directly therefrom. This requires 
the building of new cameras but so does the use of 70 mm. film. 
Another method of recording wide film consists of recording on 
35 mm. film in the regular cameras, optically condensing the picture 
laterally during recording, and then optically printing normal pic- 
tures on 70 mm. film for the de luxe houses as well as optically printing 
normal pictures on 35 mm. film for the small houses. This can be 
accomplished by using bi-convex lenses, now standard products, 
which do not seem any different from ordinary printing lenses. In 
the final analysis we believe that all pictures will be recorded on 
70 mm. film in the 1 to 1.8 ratio suggested, directly printed for the 
de luxe releases while for the smaller houses the 70 mm. pictures will 
be optically printed on 35 mm. film in the 3 to 4 regular ratio. This 
will make the objects appear slightly more slender than normal, 
an attribute for which all actors longingly crave. Obviously the 


suggestion for using 35 and 70 mm. standards has to do with permit- 
ting the manufacturers of film to continue the production of 70 mm. 
raw stock which may be employed for 35 or 70 mm. recording or 

MR. FEAR: Gentlemen, it occured to me that you might be 
quite as interested in what we are doing in Hollywood as in the 
theoretical discussion of wide film. You have already seen two ex- 
periments, one of which was Happy Days, and soon you will see The 
Big Trail one of the finest picture epics ever made, due to the photog- 
raphy and wide film. Wide film furnishes a clear background; you 
will see close-ups and yet miles away there will be clearly defined re- 
sults. This can only be accomplished on wide film. Big pictures 
and equipment cannot be installed in all theaters without properly 
considering the economic side of the question. The producers in 
Hollywood are trying to find the solution. The wide pictures pro- 
duced cost too much to show. In one case special cameras had to 
be bought, but no projectors were available. It was suggested that 
an optically reduced print be made and shown in 35 mm. projectors. 
The man who projected it knew something about this and was so in- 
terested that this method was adopted for release prints. It con- 
sists of reducing 70 mm. to 35 mm., using the full width of the film 
and a separate sound film. Two extra sound heads are required 
for the projection machine. 

Other methods have been suggested, such as rebuilding the pres- 
ent equipment; this is feasible, but may involve considerable cost. 
In designing projectors there is a definite practical width which 
limits that of the film ; it is the widest width of film that can possibly 
pass through the projector without rebuilding the latter. That width 
is 50 mm. If a film of that width is used the height must be consid- 
ered. It is impracticable to use a higher picture in the theaters 
than is used at present, so it resolves itself into widening the pictures. 
The solution, then, is a 35 mm. film widened out. This is the answer 
to the controversy on wide film in Hollywood. It applies only to 
release prints. 

PRESIDENT CRABTREE: Is Mr. Powrie here? With regard to 
reducing down from wide film on to 35 mm., if you look in the Trans- 
actions of the Society for 1924, you will find a paper by Mr. Powrie 
on the subject. He demonstrated the process and practically showed 
the improved graininess obtained by that method. 

MR. Ross: If we understand Mr. Fear correctly, he stated that 


wide pictures can be photographed only onto wide film. We again 
call your attention to the fact that Mr. Fear's system produces wide 
film pictures recorded on 35 mm. film. 

MR. FEAR: The 35 mm. method I suggested last year solved the 
problem as to projection suitable for general use. The great dif- 
ficulty lies in the matter of employing untrained men. 

In Hollywood, we are producing the 65 mm. and 70 mm. cameras. 
MGM and Fox are using 70 mm. There is some difficulty which 
probably will be overcome, due to using four perforations instead of 
five. It has been suggested that five perforations be used. Warner 
Brothers, First National, and Universal are using 65 mm. cameras 
for their photography. Some prefer to make release prints on 65 
mm. film. It is desirable to eliminate the human factor as far as 
possible in all laboratory work. There should be one negative of 
constant density without light changes due to the inexperience of 
operators who are likely to miss a light change. This can be done 
only by making a larger negative 65 mm. or 70 mm. ; from this a 
master positive is made and corrected for light change. An expert 
technician should do this. Then an optically reduced duplicate 
negative is produced. This optically reduced negative will be su- 
perior in quality to an original of the same size because of the reduc- 
tion of grain in such an optical print. 

I think that answers your question ; it is an economic problem. 

MR. Ross: I merely wish to add that in suitably reconstructed 
printers no prisms are required. Further, the question of making 
dupe negatives or fixed density positives seems to be apart from the 
question of wide film. 

MR. GRIFFIN: The suggestion has been made that it is a good plan 
to reduce optically from a wide negative to 35 mm. film. I have 
seen pictures projected which were made in this manner and as 
far as pictorial quality is concerned the result is very good. It 
must not be forgotten, however, that the problem of projecting this 
type of picture to a screen 40 ft. wide is highly impracticable because 
it is impossible to pass the necessary amount of light through the 
small aperture. The size of the aperture in this case is approxi- 
mately 0.940 wide by half that in height. Using 135 amperes at 
high intensity and condensers of the most improved design, it is im- 
possible to procure more than half the illumination on the screen that 
is acceptable for the projection of standard film, and it is necessary 
that the projectionist be on the alert at all times to constantly secure 


even this result. It must also be remembered that this reduction 
print, running as it does across the film from sprocket hole to sprocket 
hole, allows for no sound track and it is necessary to record on either 
disk or separate film, which adds considerably to the cost of ap- 
paratus necessary for sound reproduction, to say nothing of the 
errors in synchronizing which may and do arise frequently under this 
system. I don't think the solution lies in using 35 mm. reduced 
prints. I feel that the industry should certainly consider going to a 
film of, perhaps, 50 mm., in which all the excellent quality obtainable 
in wide negatives can be incorporated and which we know can be 
satisfactorily projected. By adopting such a dimension all the pro- 
jectors now in use could be converted to handle this size as well 
as 35 mm. film at comparatively little cost to the exhibitor com- 
pared with the cost of equipment for the wide film as we now know it. 
Such a standard would be economically sound and enable the pro- 
duction of wide film to go ahead without a great deal of delay. Our 
corporation has spent a tremendous amount of money on film equip- 
ment and wide films but I am sure we should be willing to discard 
this for a standard which is economically sound and which allows 
the salvaging of the greater part of equipment at present in use. 

MR. STERN: I should like to know if Billy the Kid was produced 
by making a 35 mm. print from the 70 mm., or was it an optical print 
from a 70 mm. negative? 

MR. FEAR: It was produced by original reduction of the negative 
to the positive. On such a huge reduction, it is almost impossible 
to utilize the method I outlined before. I have a company in produc- 
tion on a wide film picture with four more to start in the next 90 days, 
which will be released to the independent exhibitor. We are making 
plans for a patent license to rebuild projection machines for a certain 
size film and are anxious to have a standard to adopt. In our system 
of conversion of projectors, the 35 mm. sprocket is cut in two so that 
the film is run throughout in the extensible position. We have added 
space between the sprockets. By moving levers we can change from 
one film to the other. The method is extremely inexpensive. 

MR. Ross: I wish to call attention to the fact that the frames in 
Billy the Kid are about one-third smaller in height than in standard 
35 mm. film and that, therefore, in the systems in which we have 
suggested using standard size frames there will be available one- 
third more light, or aq average of approximately 7 foot candles. 
Furthermore, whereas the foot candles have been reduced from, say, 


11 to 7, the picture viewed has approximately twice the area and 
there will be as much illumination at an intensity of 7 foot candles on 
wide pictures as at 11 foot candles on regular size pictures. We 
believe that if the wide screen pictures were to be projected with an 
average screen intensity of 11 foot candles, the amount of light 
reflected by the screen would be objectionable to the audience, 
especially to those in the rear portion of the auditorium. Further- 
more, with quick changes of scene the light and shadows reflected 
onto the walls of the auditorium would also be objectionable. 

PRESIDENT CRABTREE: What technical difficulties have been 
encountered in the handling of wide film in Hollywood? 

MR. FEAR: In Hollywood, everybody is enthusiastic about wide 
film. The producers are a little anxious about the situation because 
they want to know what is going to be done about it. No cameras are 
being sold for 35 mm. film. I will not sell them because I know we 
are going to a new standard and they will become obsolete in a short 
time. United Artists, Warner Brothers, First National, Fox, MGM, 
and Universal are working on wide film at the present time. One of 
my cameramen, Mr. J. O. Taylor, started on another picture last 
week. Every producer out there is awaiting your decision. It is 
highly improbable that every producer will have a different standard. 
In the majority of cases where we have handled wide film we have 
not had any technical difficulty. It is handled the same as the other, 
and the cameras have caused no more trouble than the others. The 
cameraman shoots a little differently from the 35 mm., but the main 
difficulty lies in projection. 

MR. GRIFFIN: Mr. Fear said that difficulty has been experienced 
on the Coast in the projection of wide pictures. I know that to be so 
but I believe it is because the improper condenser combinations were 
used and improper distances were maintained between the arc and 
condensers and the condensers and aperture. We in the East are 
closer to the optical manufacturing organizations and lamp manu- 
facturers and close cooperation has enabled us to obtain satisfactory 
results more quickly. All of the data obtained have been forwarded 
to the Pacific Coast and I have word that they are getting far better 
results than formerly. I don't think there is any difficulty now with 
the projection of wide film but certainly a film of approximately 50mm. 
width would eliminate any slight difficulty which might be experi- 

Sept. 30, 1929, to Oct. 1, 1930. 

This report covers the term of the fiscal year beginning October 
1, 1929, and ending September 30, 1930. During the first four 
months of the period covered by this report, the affairs of the Secre- 
tary were conducted by Mr. R. S. Burnap. Changes in the business 
administration of the company with which he was connected required 
his resignation from the office of secretary on February 9, 1930. 
Thereupon, at the invitation of the Board of Governors, the writer 
assumed the duties of the secretary's office for the remainder of the 


The total membership of the Society, as of the last day of the past 
fiscal year, is 756 members, divided as follows : 

Eight Honorary members. These are : 

Mr. George Eastman, Rochester, New York. 

Mr. Thomas A. Edison, West Orange, New Jersey. 

Dr. F. E. Ives, Philadelphia, Pa. 

Mr. C. Francis Jenkins, the founder of the Society, Washington, D.C. 

Mr. Louis Lumiere, Paris, France. 

The Presidency, Societe* Franchise de Photographic, Paris, France. 

The Presidency, Die Deutsche Kinotechnische Gesellschaft, Berlin, 

The Presidency, Royal Photographic Society, London, England. 

There are 371 Active members, and 377 Associate members. And, 
in addition, there are 14 sustaining members consisting of various 
commercial and industrial organizations. 


Of the Society's membership 664 are under the jurisdiction of 
four local sections, with headquarters in New York, N. Y.; Chicago, 
111. ; Hollywood, Calif. ; and London, England. The distribution of 
members among these four sections is as follows : 

* Presented at the Fall 1930 Meeting, New York, N. Y. 


New York Section 182 Active, 175 Associate 

Chicago Section 29 Active, 48 Associate 

Pacific Coast Section 61 Active, 47 Associate 
London Section 71 Active, 51 Associate 

The combined territory of the three American Sections covers the 
entire United States, exclusive of territorial possessions. The terri- 
torial limits of the several sections were defined by the Board of 
Governors as follows: 

The United States is divided from East to West into three geo- 
graphical sections by drawing two north and south parallels. One 
of these lies fifty miles west of Cleveland, Ohio, and the other fifty 
miles west of Denver, Colorado. That part of the United States 
lying east of the first-named parallel comprises the territory of the 
New York Section; that part of the United States lying west of the 
second-named parallel comprises the territory of the Pacific Coast 
Section ; the area intermediate between the two parallels constitutes 
the territory of the Chicago Section. 

The territory of the London Section remains unchanged as con- 
sisting of the British Isles. 

There are 84 members of the Society, residing in 18 foreign coun- 
tries, not including Great Britain, who do not come under the juris- 
diction of any local Section. The membership distribution among 
these countries follows: 

Active Associate 

Argentina 1 

Australia 2 

Brazil 1 

Burma 1 

Canada 5 10 

France 7 11 

Germany 8 9 

Holland 1 

India 5 5 

Italy 1 2 

Japan 1 3 

New Zealand 2 

Norway 1 

Poland 1 1 

Russia 2 

South Africa 1 

Sweden 1 

Switzerland - 1 


Territorial possessions of the United States provide one associate 
member who resides in the Philippine Islands. 

In addition to the above, there are pending, 20 applications for 
Active membership, and 25 applications for Associate membership. 

During this term 7 Active members and 4 Associates resigned; 
10 Active members and 19 Associates were dropped for non-payment 
of dues ; 3 Active members were transferred to Associate membership, 
and 2 Associate members were transferred to Active membership. 


The large increase in membership during the past year was primar- 
ily due to increased interest in the Society's JOURNAL, now published 
monthly; a more widespread knowledge of the Society's aims and 
accomplishments; and the noteworthy activity of the Membership 
Committee. A total of 199 new members were admitted during this 
past year to the Society. The sectional distribution of these new 
members is as follows : 

New York Section 77 

Chicago Section 21 

Pacific Coast Section 23 

London Section 38 

Foreign countries, not including Great Britain, 40. 


While the number of annual subscriptions to the JOURNAL is not in- 
creasing as rapidly as was at first expected, satisfactory progress is 
being made in this direction. Subscriptions total 202, of which 173 
are paid, 4 are free to Local Sections, 11 are exchanges with other 
publications, and 14 are free to sustaining members. 


Total sales of single copies of the nine issues of the JOURNAL to date, 
exclusive of the October issue, numbered 52, as contrasted with 1030 
copies of back numbers of the Transactions, sold during the past 
fiscal year. 


After many months of negotiation with the Post Office Department, 
your Secretary is especially pleased to report that second class postal 
privileges have at last been granted to our Society in the matter of 
mailing the monthly JOURNAL. By reason of obtaining this privilege, 
which was granted only after certain requirements of the Post Office 


Department were met, a considerable saving in the cost of mailing 
the JOURNAL will be effected in the future, in addition to our obtain- 
ing a substantial refund on the mailing of past issues. 

One of the more important changes required by the Post Office 
Department was in the matter of the subscription price to members 
of the Society. The ten dollar allowance for annual subscription to 
members was changed to nine dollars to make it less than the amount 
of the annual dues for Associate members. Notice to this effect is to 
be incorporated in new application blanks which will shortly be 

Respectfully submitted, 

J. H. KURLANDER, Secretary 


It is very necessary that all members of the Society and subscrib- 
ers to the JOURNAL immediately advise the General Office of the 
Society, when a change in mailing address is made. Otherwise, when 
literature is returned by the Post Office for this reason, the member's 
or subscriber's name is removed from the mailing list for the JOURNAL 
until the proper address is obtained. Future issues of the JOURNAL 
will contain, from time to time, lists of members or subscribers for 
whom no address is known. Anyone knowing the whereabouts of 
those members or subscribers is requested to advise the General Office 



October, 1930 

In this report an attempt will be made to set forth the manner 
GINEERS has been conducted since its establishment in January, 1930. 

Following the autumn convention of 1929, at which time the 
publication of a journal was authorized by the Board of Governors, 
immediate steps were taken to set up the necessary machinery 
for publishing this journal at regular monthly intervals. The 
requirements and problems of publishing a technical journal were 
discussed with several publishing houses and bids on cost of publica- 
tion were requested from two or three of those which to the committee 
appeared most capable of handling this work. After careful con- 
sideration a contract was signed with the Mack Printing Company 
of Easton, Pa. The decision of the committee to give the contract 
to this concern was based not only upon its bid on cost, but also 
upon its proximity to the cities in which are located the editorial 
office and the offices of the secretary and treasurer. 

The question of general style, typography, etc., was discussed at 
considerable length with the publisher and a style sheet was com- 
piled to serve as a guide in obtaining uniformity of style throughout 

An attempt was made to get the machinery of publishing estab- 
lished sufficiently early so that the first issue could appear on January 
1. As a matter of fact the January issue was a few days late but 
was mailed during the first week of the month. Since that time, 
with perhaps one exception, the JOURNAL has been mailed from the 
office of publication prior to the first of each month and in most cases 
has reached the members and subscribers within the first few days of 
each month. 

The committee has endeavored to keep the contents of the JOURNAL 
in harmony with the wishes of the Board of Governors as expressed 
specifically in the resolutions passed at the time the decision was 


made to publish the JOURNAL. A statement of the material to be 
incorporated in the JOURNAL will be found in the JOURNAL XIV (Janu- 
ary, 1930) p. 8, under item 5. 

In Table I following will be found an analysis of the contents of 
the JOURNAL up to and including September, 1930. The first section 
of the table analyzes the contents in terms of numbers of pages. The 
totals at the extreme right of the table indicate the way in which the 
space of the JOURNAL has been utilized. In the first nine issues a total 
of 1130 pages have been published, of which 895 were devoted to 
purely technical papers; 36 pages to abstracts of scientific articles 
which, in the opinion of the editorial office, should be of interest to 
the membership; 9 pages to book reviews; and 168 pages to society 
notes, tables of officers, committees, photographs of officers and 
committees, and material of general interest to the Society but of a 
non- technical nature. The committee feels that this disposition 
of the space is fairly well in accord with the wishes of the Society 
as set forth by its Board of Governors. 


Jan. Feb. March April May June July Aug. Sept. Total 

Analysis of Contents in Terms of Pages 

108 895 

4 36 

1 9 

22 168 
3 22 
138 1130 

11 67 

11 80 

13 169 

1 17 

The second part of the table shows an analysis of contents in 
terms of material. Again in the total column it will be seen that 
of the total scientific papers published, 67, were obtained from our 
two semi-annual conventions, while 6 were contributed directly to 
the editorial office. Six committee reports were published and 3 

Technical Papers 


















Book Reviews 







Society Notes, Com- 

mittees, etc. 


















Total pages 









Analysis of 


in Terms of Material 

Convention Papers 









Contributed Papers 





Committee Reports 




. . 

. . 




. . 

. . 



Total No. Papers 





. 6 













Book Reviews 







Reprints ordered 

2500 940 








translated foreign articles, making a total of 80 scientific papers. The 
number of abstracts was 169 and book reviews 17. 

In the last section of the table are shown the number of reprints 
which have been ordered from each month's publication. For 
the nine months covered by this table a total of 23,840 reprints have 
been ordered. 

We now come to the very important question of how much the 
JOURNAL is costing the Society. In Table II will be found an analysis 
of the costs involved in publishing the first nine issues (January to 
September, inclusive) of the JOURNAL. In the first column will be 
found the number of copies printed for each month and in the second 
column the total number of pages in each month's issue. In the 
third column are shown the amounts directly chargeable to "editorial" 




Pages Editorial 

Printing Cuts 



Cost Postage 



































123 . 10 
























































































work. This includes the preliminary preparation of the manuscript 
for the printer. It should be pointed out that many of the manu- 
scripts as received by the editorial office require considerable work 
before they are in shape to be sent to the publisher. In some cases 
the drawings and illustrations submitted by the author are not 
satisfactory for reproduction. In some cases the editorial office 
has assumed the responsibility of having these redrawn, while in 
other cases they have been returned to the authors for correction. 
This item also includes all proof-reading, both of the galley and page. 
It includes all stenographic work and amounts paid out for the trans- 
lation of foreign articles. The item does not include any charges 
for postage, telegrams, and long distance telephone messages. These 
items were absorbed by the office of the editor pro tern and paid by 


the company by which he is employed. It is estimated that the 
total amount chargeable to these items up to the present time is 
not over $75.00. In the last column will be found the monthly cost 
of printing the JOURNAL. This includes all charges made by the pub- 
lisher with the exception of cuts and postage. In the next column 
are shown the monthly costs chargeable to the making of cuts for 
the illustrations of the JOURNAL, and in the next column a total of 
these two items which represents the actual cost of printing the 
JOURNAL. The monthly postage bills chargeable directly to the mail- 
ing of the JOURNAL are shown in the column so designated. In the 
last two columns of the table are shown the cost to the Society of the 
reprints ordered by the various contributors and the postage involved 
in sending these out. 

In arriving at the total cost of the JOURNAL for the first nine months, 
we must include the following items: 

Editorial $1013.00 

Publisher 6504.75 

Postage 551.82 

Reprints 1057.66 

Postage on reprint 69 . 17 


Since reprints are billed to the author at cost plus 50 per cent, the 
profit on reprints should be subtracted from the above figure. This 
profit is $528.83. Subtracting this from the total cost we find that 
the JOURNAL for the first nine months has actually cost the Society 

Let us turn again for a moment to the consideration of Table I 
in which the analysis of content is shown. It will be noted that of 
the total number of technical papers published only six may be 
classed as contributed, all the remaining material of this type being 
derived from the 1929 autumn and the 1930 spring conventions. 
The JOURNAL Committee had hoped that as soon as a monthly journal 
had been established there would be a goodly number of contributions 
other than papers read at conventions. We feel that in the future 
there will be more material of this character. There can be no doubt 
that in many cases the results of experimental and research work 
going on in various localities mature and are ready for publication 
at times between our semi-annual meetings. The JOURNAL Com- 
mittee would like to encourage authors to submit manuscripts 


at any time. It is probable that greater activity on the part of 
the editor of the JOURNAL will be required to unearth this potential 
material. It would seem desirable to keep the number of pages 
published each month at a fairly constant level. We therefore hope 
that in the future more contributed papers will be available. 


Members and Samples and 
Month Subscribers Back Orders Stock Special Total 

Jan. 661 497 770 300 2228 

Feb. 705 246 1081 45 2087 

March 759 223 913 100 1985 

April 809 195 1020 25 2049 

May 769 238 1100 60 2157 

June 834 111 1089 45 2079 

July 871 147 1068 35 2121 

Aug. 908 76 1075 45 2104 

Sept. 951 68 1068 20 2107 

Total 7267 1801 

Moreover there is undoubtedly a large number of foreign articles 
which are well worth translating and printing in the JOURNAL. Here 
again, a regular editor with more time to devote to the search for 
such material would be an advantage. We should also like to see an 
expansion of the abstract section and an increase in the number of 
book reviews, provided books of sufficient value continue to appear 
from time to time as they undoubtedly will. It seems reasonable 
at the present time to plan upon a journal of approximately 150 
pages per month. It will be noted that within the past nine months 
several of the issues have fallen considerably below this number of 
pages. If we assume a 150 page issue each month there is therefore 
space to accommodate more contributed and translated articles and 
some expansion of the abstract and book review sections. 

The committee feels that the most important step now in the 
evolution of the JOURNAL is the appointment of an editor with suitable 
assistants to carry on the work and to develop the JOURNAL along the 
general lines as indicated. 

LOYD A. JONES, Chairman 




The present Publicity Committee was appointed directly following 
the Fall Meeting of 1929 at Toronto and has been actively function- 
ing since that time. 

The work of the committee naturally divides itself into two parts, 
namely: providing news to the trade press and newspapers of the 
semi-annual meeting and the activities of the Society throughout 
the year. 

The present Publicity Committee has served during one meeting, 
the May, 1930, meeting at Washington, D. C. At this meeting 
two news releases were issued each day of the Convention. As a 
result of this work at the May Meeting, 1400 inches of news or ap- 
proximately 20 newspaper columns were carried by trade papers and 
newspapers of which the Publicity Committee has accurate record. 
However, it is certain that a great deal more space was obtained 
since several of the stories were put on Associated Press and United 
Press wires and published in many newspapers throughout the 

In furnishing news of the activities of the Society between con- 
ventions, the Publicity Committee has released more than 25 stories 
to the trade press. 

When a story is released it is sent to all trade papers in the United 
States, all technical journals dealing with the motion picture in- 
dustry, and foreign motion picture trade papers and technical jour- 
nals. The list includes more than 30 publications altogether. 
Special stories have also been written for a number of publications, 
and reports of the May meeting were supplied to a number of tech- 
nical journals. Abstracts of all papers read at the May meeting were 
mimeographed and supplied to papers in this country and abroad. 

Another duty of the Publicity Committee was to establish ex- 
changes of the Society's monthly JOURNAL with more than 30 motion 
picture and technical publications in this country and abroad. This 
exchange of publications has resulted in a great deal of publicity not 
only in this country but in some of the finest technical journals in 
European and other foreign countries. 

Whatever success the present Publicity Committee may have ob- 

* Presented at the Fall 1930 Meeting, New York, N. Y. 


tained has been due not so much to its own work as to the splendid 
cooperation given by the motion picture trade-press. The Publicity 
Committee has found that the motion picture trade-press is extremely 
willing to offer every possible cooperation in publishing news regard- 
ing the activities of the Society and that its pages are always open for 
any legitimate news concerning the Society. 

The Publicity Committee therefore wishes to express its apprecia- 
tion to the motion picture trade-press for its splendid cooperation 
in reporting the activities of the Society. 

The Publicity Committee also wishes to thank all those in the 
Society who have cooperated with it and who have helped to supply 
the Publicity Committee with details of the Society's activities, 
for transmission to the press for publication. 



O. A. Ross 


There has been little change in the methods of studio lighting 
since the report given at the Washington convention last May with 
but one exception, that there seems to be a tendency on the part of 
many of the studios, where incandescent lighting has been used to 
a very large extent, to increase the number of high intensity spots 
and sun arcs for floodlighting purposes. This has been rendered 
possible by the efficient silencing devices which have been installed on 
d. c. generating equipment and arc lamps in the various studios. 

Manufacturers of arc lamp equipment are advertising new equip- 
ment for high intensity arcs which is claimed to be free from many 
of the causes of noise present in the older lamps. 

None of the information which your committee has been able to 
obtain in the past six months is of a character which advances the 
real knowledge of studio lighting to any considerable extent. Basic 
information which is available with regard to the various sources 

* Presented at the Fall 1930 Meeting, New York, N. Y. 


of light is given in many articles which have appeared in the Trans- 
actions of the Society, of which a bibliography was presented in the 
last committee report. Much additional knowledge can be obtained 
from the studios themselves, but in spite of very earnest efforts of the 
committee it has been impossible to obtain this information up to 
the present time. 

We understand that in past years attempts have been made to 
utilize photometric measuring devices in the studios, but that none 
have been found satisfactory or useful for one reason or another. 
Some recent work has again been done on this problem, but up to the 
present time little progress has been made in the practical applica- 
tion of these instruments. 

Continued efforts on the part of the committee should be made to 
obtain information from the studios which will permit the establish- 
ment of standards for desirable levels and types of illumination for 
the various kinds of sets encountered in the production of motion 
pictures. The methods which can be applied in this work probably 
lie in the determination of levels of illumination coupled with the 
photographic values of the light actually used and micro-density 
determinations on films taken with the various types and mixtures 
of illuminants. 

A. C. DOWNES, Chairman 


The May report of the committee gave a list of producers of color 
pictures and the systems used. At that time the Photocolor Cor- 
poration 1 report had not been received. Mr. A. G. Waddingham, 
technical director of the corporation, supplied the following descrip- 
tion of this system: 

"The color camera is of special design, photographing a pair of 
images in conjunction with special taking-filters and an optical sys- 
tem employing the split beam method of photographing. 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
1 Letter dated July 11, 1930. 


"The negative is printed upon a specially designed optical printer 
which prints the two respective images upon duplitized positive 

"The print is then transferred to the green processing room where 
the film receives an application of the blue-green complementary 
dye on the side containing the image from the red sensation negative. 

"It then passes through a red processing machine, wherein the 
orange-red dye is applied to the image from the green sensation nega- 
tive. At the termination of this operation the film is removed and 
sent to the assembly room where it is assembled and finally projected 
and inspected upon the screen." 

According to Mr. Waddingham, the process is adaptable for the 
production of sound prints in color, either by the disk method or the 
sound-track on film method. The company is equipped with a 
thoroughly up-to-date laboratory, and a new sound studio is in the 
course of construction. 

The Reporter, Hollywood, October 8, 1930, says the Photo- 
color Corporation of New York is planning to build a plant in Holly- 
wood with a capacity of a million feet of film a week and expects to 
be in operation soon after the first of the year. 


A specially made negative is being marketed, for use with the Film 
Pack system, known as Red Ortho Front Negative. 2 This has a 
blue sensitive emulsion on the surface of which is a layer containing 
a red coloring matter. 

In making color sensation negatives by this system, Red Ortho and 
a panchromatic negative are placed emulsion to emulsion in the 
camera and exposed simultaneously. The light from the lens passes 
through the Red Ortho, recording the blue end of the spectrum. 
The red colored layer then filters out the blue; the red end of the 
spectrum passing through is recorded by the panchromatic negative. 

The red coloring matter on the Red Ortho is removed from the de- 
veloped, fixed, and washed negative by bathing in a 3 per cent solution 
of hydrosulfite of soda. 


A new color process is being introduced from Germany, known as 
the "New Color Process." It is claimed that this is usable for either 
motion picture or stills, although in the description the method of 
using it for motion pictures was omitted. 

2 English Provisional Patent No. 333,933, August 25, 1930. 


Successive exposures are made in a special camera fitted with tri- 
color filters. The color value negatives are printed on positive films 
which have their respective dyes incorporated in the emulsions. The 
films are then developed, fixed, washed, and subjected to a warm 
water treatment. No formulas were given. The silver images are 
then reduced, leaving pure dyed images which, it is claimed, can be 
either transferred to an individual support, or the three films can 
be placed in register and bound. The printing is accomplished by 
printing through the celluloid side of the film. 


In the Herault Color Process a three-color sector wheel is rotated 
in front of the camera and the contact print negative is dye tinted so 
that each successive group of frames is tinted one of the primary 
colors. The three-color positive is then projected with a continuous 
projector (Continsouza-Combes) . The method is said to suppress 
the chromatic flicker when projected at 24 frames per second; only 
spherical lenses are used in this projector. This plan is somewhat 
similar to that now being suggested by Wolf-Heide. 


In this system three pictures are taken simultaneously with three- 
color filters, using a prism system in the camera. In the positive, 
each frame carries three images, each corresponding to one of the 
color separation images of the negative. This method is being 
sponsored in Great Britain by Universal Productions, Ltd. 


In a report from Dr. Walter Clark, London, August, 1930, he states 
that "a number of color cinematography processes are being investi- 
gated in England and a few productions are in progress utilizing some 
of them. Processes being studied or used in England include Pathe- 
color, Talkie-Color, Zoechrome, Dufay, and Raycol." 


In a paper entitled "The Chromolinoscope Revived," Dr. H. E. 
Ives has described several applications of the instrument devised by 
his father, F. E. Ives, in 1901. This instrument was devised for the 
production of line images by the use of a special ribbed glass inserted 
in the optical system. Methods of making "ridged" images and 



[J. S. M. P. E. 

ridged film records from three-color separation negatives are described 
as well as a method of copying film (such as Kodacolor) containing line 
images. /. Opt. Soc. Amer., June, 1930, Vol. 20, p. 343. 


A review of recent advances in color photography is published by 
G. Grote in the Photo gr aphis che Korrespondenz, April, 1930, Vol. 66, 
p. 91. 


Dr. N. M. LaPorte of the Paramount Publix Corporation says, 
"relative to our experience with the Keller-Dorian method, would 
say that while our preliminary investigations show that there is con- 
siderable merit to the process, we have not made any commerciaJ 
takes to date." 


A camera gate that holds two films in contact while at the aperture 
gate in a camera and suited for composite photograph and film pack 
color negatives has been issued in England. The gate seems specially 
suited for Bell & Howell cameras and is known to produce very ex- 
cellent results. 


The Glorious Adventure, first of 
the full length, full color pictures to 
see the light of day, was shown some 
ten years after its original debut at 
the Filmarte Theater, 1228 Vine 
Street, Hollywood, California, for a 
week beginning August 15, 1930. 
It received favorable comments 
from the press. 


A demonstration reel, colored by 
the Multicolor System, was shown 
here last night. The negatives were 

1 September 23, 1930. 

4 August 25, 1930, No. 333,932. 

Camera gate for film pack. 

Jan., 1931] COMMITTEE REPORTS 101 

made by the Film Pack System and most of the scenes exhibited 
were made under artificial light. 


An exhibition of work done by the Sennett Laboratories, Studio 
City, California, was shown last night. All the negatives are made 
by the Film Pack system. The aim here, according to the Sennett 
organization, is to produce films with good photography and sub- 
dued color. 


This system gives wide film sound and color. It is an additive 
method with many of the old features utilized, but designed to rid 
itself of color bombardment and color fringing. 

This is accomplished by having the film pass through the normal 
projector at the standard speed of 90 feet a minute with an intermit- 
tent movement, using an 8 sided cam instead of the usual 4 sided 
cam. This gives 48 pictures a second of half the usual height, 
instead of 24 full frame pictures a second as is customary. At this 
speed of 48 changes a second, there is little or no color bombard- 

The negatives are preferably made by the film pack system. The 
only change in the camera is that it is fitted with a half size aperture 
gate, and the normal speed of 24 pictures a second insures good ex- 
posures. Other methods of making the negatives may be used. 

For the positives, the negatives, which have been exposed as above 
described, are printed in sequence, giving on projection a series of 
48 pictures a second, with the sound at 90 feet a minute giving perfect 
reproduction. No fringing is discernible as the negatives have been 
made in pairs. In addition to this the film is tinted with alternate 
spaces of red and blue-green, so that after leaving the laboratory the 
films cannot be joined or run out of color. 

No public demonstrations have been given although private ex- 
hibitions have brought forth encomiums. As the process has no 
toning, using black and white pictures, and makes use of a process in 
which the problems are familiar and well worked out, the film can 
be introduced at low cost. 

The above description covers much that has been done but, as 
many changes are being made, no demonstration will be given until 
the Spring Meeting of the Society. 


Mr. Roy Hunter of Universal Films, Inc., who has been active in 
the development of the Magnachrome System has supervised the 
making of a two reel picture without color using this method of 

WM. V. D. KELLEY, Chairman 


On account of the recent appointment of the speaker to the Chair- 
manship of the Historical Committee of the Society of Motion Picture 
Engineers, it was found impossible to hold a meeting of the committee 
at which more than three members could attend at any one time. 
In spite of the fact that it was not possible to bring together the mem- 
bers of the committee for a formal meeting a considerable amount of 
work has been accomplished by conferences of the Chairman with 
the various individual members of the committee. 

A schedule of the matters at present under consideration by the 
committee was sent by the Chairman to each individual member and 
replies have been obtained from all members of the committee re- 
siding in the United States. 

The principal questions being considered by the Historical Com- 
mittee at the present time are : 

1. The selection of a museum as a repository for whatever speci- 
mens of a historical nature can be collected by the Society. 

2. Consideration of a means for recognition by the Society of sur- 
viving pioneers who were active in the establishment of the motion 
picture industry. 

3. The locating and obtaining, if possible, of any and all relics, 
films, and documents of importance concerned with the early history 
of the industry. 

4. Planning for the future work of the committee. 

That is a brief synopsis of the problems which have so far been 
considered by the committee. 

Ever since the formation of the Society there has been more or less 
talk about the necessity of preserving in some manner the various 

* Presented at the Fall 1930 Meeting, New York, N. Y. 

Jan., 1931] COMMITTEE REPORTS 103 

relics, documents, and early films which represent the various stages 
of development of cinematography. 

Although we are just beginning to be ashamed of referring to 
cinematography as an infant industry, nevertheless more than forty 
years have passed since the first chrono-photographic records Were 
made and a great many steps in the development of motion pictures 
have passed into the limbo of forgotten things. The objects and aims 
of the Society place it automatically in the position of being best 
suited for the task of preserving the history of the industry. The 
Historical Committee has, therefore, considered very carefully the 
problem of a suitable repository for whatever specimens of a histori- 
cal nature can be collected. 

Most museums exhibit a definite class of objects and are thus auto- 
matically eliminated from consideration. The museums under con- 
sideration are those who have signified that they would like to obtain 
whatever motion picture exhibits which can be given by the Society. 
They are the Museum of Peaceful Arts, New York, Smithsonian 
Institute, Washington, D. C., Julius Rosenwald Museum of Science 
and Industry, and the Museum of the University of Southern Cali- 
fornia, Los Angeles, Calif. The committee believes that the museum 
best fitted for the purpose is the one which is most easily accessible to 
the greatest number of people interested in the motion picture indus- 
try. New York City is unquestionably the world center of the motion 
picture business, even though the majority of pictures are not pro- 
duced in the vicinity of New York. The Museum of Peaceful Arts is 
at present housed in the New York Daily News Building at 220 
East 42nd Street, accessible in a few minutes from the center of New 
York City. While it is a new museum and not yet well known to the 
public, its plans for future development look forward to a skyscraper 
museum in the center of the city, easily accessible to visitors with a 
limited amount of time. It is being developed along the latest and 
most approved methods of museum exhibition, wherein the exhibits 
are displayed in the best possible manner. Wherever possible the 
exhibits are mechanically operated either by motor, actuated by 
a push button pressed by the spectator, or by means of a crank 
operated by the observer. At the same time the exhibit is protected 
in a suitable glass case. 

The space available in the Smithsonian Institute is limited. The 
ability of the museum to do certain things is also limited by the 
Federal law which governs it. Moreover, the number of visitors to 


the Smithsonian Institute is limited. Most of these objections also 
apply to the other museums mentioned above. 

As there does not appear to be any central museum available at the 
present time for the housing of what we hope will in time prove to be 
a considerable collection, it has been suggested that whatever material 
may be available at the present time be divided among those museums 
best suited for the present purpose as loan exhibits so that, should a 
more suitable place be found in the future for a central exhibit, the 
loans could be recalled and all of the collections be assembled in one 

The Museum of Peaceful Arts has signified its willingness to accept 
exhibits on loan so that the Society at any time can withdraw ex- 
hibits allotted them and replace them in any more suitable place which 
may be selected in the future. 

While the Historical Committee has no knowledge at the present 
time of any historical relics being presented to the Society for museum 
exhibition, a great amount of material has been located and it is 
believed that as soon as a suitable repository has been selected that 
it will not be difficult to obtain a very considerable array of objects 
of great interest concerning the development of the industry. 

The matter of recognizing in some manner the pioneers of the in- 
dustry has been taken up with the Board of Governors. The com- 
mittee has investigated the careers of Jean Acme Leroy and of Eugene 
Augustin Lauste. Jean Acme Leroy seems to have been the first 
man to project pictures on a screen with a machine operating on the 
same principles as those in use today and Eugene Augustin Lauste 
took out the first patent for sound record on film. 

Several of the members of the Historical Committee have investi- 
gated the lives of these two old men, whose advanced age makes it 
seem probable that they will not be with us much longer, and whose 
claims have been under consideration by the Society for over a year 
without definite action being taken. 

Their friends in the Society think that their careers should be 
recognized in the form of an honorary membership for each of them. 
Others have maintained that although these men may have been 
pioneers, this might establish a poor precedent and perhaps may later 
cause embarrassment to the Society by the request of a large number 
of others for the same sort of recognition. 

This seems an unfair argument. The Society has already in the 
past honored various persons of prominence in the early history of 

Jan., 1931] COMMITTEE REPORTS 105 

the industry with honorary membership and the surviving pioneers of 
the industry are fast being decimated by the hand of time. Why 
should the Society not honor itself by extending to any pioneer of the 
industry who has materially helped in its advancement the epilogue of 
an honorary membership for their pioneer efforts? Only a few of 
these old men have reaped financial reward for the work which they 
have done and it does seem a shame that these few remaining pio- 
neers who built the foundation of this great industry should be 
pointedly ignored and turned down. 

Contrary to the unanimous recommendation of the preceding His- 
torical Committee and a reeinforced recommendation by the present 
Committee, the Board of Governors at a meeting held October 19, 
1930, refused to act on the report of the committee. 

The future work of the committee seems to be very clearly de- 
nned in the selection of a suitable repository for the historical material 
to be collected; in the location and collection of this material, and 
in planning for the foundation of a fund by some means or other to 
meet the expense connected with this work. 

Respectfully submitted, 

C. L. GREGORY, Chairman 




In any historical outline of the important inventions which have contributed to 
the technical development of motion pictures those of Eugene Augustin Lauste, 
pioneer experimenter in sound-film processes, ought properly to have a prominent 

They are unique, in that they relate directly not only to one, but to two periods 
of the utmost importance in the evolution of the modern screen. Mr. Lauste 
contributed to the early mechanical inventions which made the silent motion 
picture possible and later developed the fundamental theories which made prac- 
tical the addition of synchronized sound to the animated scene upon the same 
film. In both these fields this modest Frenchman played by no means a minor 
part. He was and is in the truest sense, a pioneer a discoverer. 

* A contribution of the Historical Committee, prepared by Merritt Crawford. 


It is not possible, in this brief record, prepared on behalf of the Historical Com- 
mittee, to do more than indicate the principal contributions which he made to the 
development of the silent and the sound-film art. Nor is it possible here to quote 
all the authorities consulted by the writer in support of the now generally ac- 
cepted contention that Mr. Lauste is entitled to recognition as an experimenter 
and inventor of premier rank in film history. 

This will be done, however, in a fully documented biography, which is now being 
prepared and in which Mr. Lauste's early researches and discoveries will be amply 
set forth. 

It is sufficient to say here that published accounts of his experiments extended 
over a period of years. The testimony of many members of our Society's 
London Section, who personally observed his work at various stages of its progress 
between the years 1908 and 1916 the records of the United States Courts the 
existence of much of his early apparatus the issuance of his British patent of 
1906, covering basic means and methods for synchronously recording and re- 
producing sound and scene upon the same film all serve to furnish a most com- 
plete picture of this remarkable man's researches and definite achievements in 
motion and sound picture history. 

Mr. Lauste, who will be seventy-four his next birthday, is now living quietly 
in semi -retirement in Bloomfield, New Jersey. He has sold all his experimental 
apparatus to the Bell Telephone Laboratory, where it is expected it will eventually 
be placed on exhibition in the Bell Telephone Museum, at West and Bethune 
Streets, New York City, to take its place alongside of the epoch making inven- 
tions of Dr. Alexander Graham Bell and the long list of distinguished scientists 
and engineers who followed him in the development of sound and telephonic 
communication processes. 

Mr. Lauste was born in the Montmartre district of Paris, January 17, 1857. 
It is said that he early displayed inventive and mechanical talents of a high order, 
and it is certain that before he was twenty-three he had filed with the French 
patent office no less than 53 models and designs on a variety of devices. 

His connection with motion picture experimental and research work began in 
1887, when he joined the technical staff of Thomas A. Edison at Orange, N. J. 
He was chief mechanical assistant to William Kennedy Laurie Dickson, for many 
years chief of Mr. Edison's technical and research staff, and shared with him in 
many of the early experiments in producing animated photography, which even- 
tually resulted in the disclosure of the famous kinetoscope. 

Mr. G. F. Atwood, now in charge of the Model Department at the Bell Tele- 
phone Laboratories, who occupied a similar post with Mr. Edison in that early 
day, tells me that Mr. Lauste was rated as one of the ablest mechanics in the 
Edison organization of that period and was highly regarded by all his superiors, 
including Mr. Edison himself. His assignments were seldom blue-printed, but 
were such as might be described as requiring much more than mere mechanical 
ability, as Mr. Lauste's ingenuity and inventive talents were fully recognized. 

Mr. Lauste left the Edison organization in 1892 to develop a gasoline engine, 
which he had designed in association with another French engineer. His model 
worked, but he became discouraged and discarded it, when experts assured him 
that an engine of this type, with its noise and inflammable potentialities, could 
never be made commercial because it would not be permitted on the streets. 

Jan., 1931] 



But for this mischance he might well have figured as an inventor in the beginnings 
of the automobile as well as the motion picture. 

In 1894 he became associated with Major Woodville Latham, a teacher, who 
had become interested in the possibilities of a step-photography as disclosed by 
Mr. Edison in his kinetoscope. Major Latham, himself, had little mechanical 
knowledge or experience, but had conceived the idea of devising a projector for 
the infant film and engaged Mr. Lauste to perform the actual experimental and 
mechanical work. 

While associated with Major Latham, Mr. Lauste designed and constructed 
the first wide film projector the Eidoloscope which embodied the famous so- 
called "Latham Loop," which is a fundamental feature in all modern projection 
machines and which was an important matter in the patent litigations of a quarter 
of a century ago. Mr. Lauste also designed and built for Major Latham several 
wide film cameras and a complete printing equipment. With the Eidoloscope 
public exhibitions were given in May, 1895, at No. 153 Broadway, New York, 
and during the following summer at Coney Island in a tent on Surf Avenue. 
The pictures shown were views of the Griffo-Barnet prize-fight, which Mr. Lauste 
had photographed on the roof of the old Madison Square Garden. 

In 1896 Mr. Lauste joined the American Biograph Company, with which he 
was associated for several years, much of the time being in charge of their labora- 
tory and experimental plant near Paris, France. 

Mr. Lauste's invention of the "Loop," in connection with the projection ma- 
chine, as well as other features of the Eidoloscope, which have borne Major 
Latham's name, has been fully set forth in the testimony in the case of Edison 
vs. The American Mutoscope Company, brought in 1898 in the United States 
Circuit Court, Southern District of New York. Major Latham, Mr. Lauste, and 
Mr. Dickson, who had then left Mr. Edison's employ to become one of the foun- 
ders of the Biograph Company, all testified in this action and their testimony 
leavesd no question as to the authorship of the invention of the first wide film 
projector, the Eidoloscope. 

Mr. Dickson, in a letter written as recently as March 28, 1927, in referring to 
the early inventors in the art, says: "... full credit must be given Mr. Lauste, 
who invented the indispensable 'Loop' and the second sprocket." 

The foregoing will suffice to indicate the importance of Mr. Lauste's contribu- 
tions to the early mechanical development of the art, but his chief fame will 
doubtless eventually rest upon his work in the field of the sound-film and its proc- 

According to Mr. Lauste, himself, it was while he was employed at the Edison 
plant in 1888, that he first conceived the idea of photographing and reproducing 
sound and scene. In an old issue of the Scientific American dated May 21, 1881, 
which he found in the cellar of the Edison laboratory, he read a description by 
Dr. Alexander Graham Bell -of his invention of the Photophone - and the successful 
transmission of sound by means of radiant energy, using a microphone and se- 
lenium cell in conjunction. 

The idea fascinated Mr. Lauste and it occurred to him that the sound waves 
might be recorded photographically and then reproduced by means of a light 
sensitive cell as Dr. Bell had done. 

At first it was his idea to record the sound waves photographically upon a ribbon 


or strip of bromide paper and to reproduce them, using a mirror and reflected 
light. He had then not yet seen a sample of Mr. Eastman's film. Early in 1890, 
however, in the Edison laboratory he saw for the first time a specimen of this film 
in the Blacksmith, one of the earliest kinetoscope subjects, and at once realized 
that the commercial material was available which would solve this phase of his 

Until the year 1900, however, the pressure of other work and his limited re- 
sources prevented Mr. Lauste from making much progress with his idea. In that 
year he made his first "light gate" of the grate type and drafted some sketches. 
But it was not until 1904 that he was enabled to build his first complete apparatus 
for experimental purposes. 

It was very crude, but it demonstrated to him that he was following the right 
lines and on August 11, 1906, he applied at the British Patent Office for an inven- 
tion described in its preliminary specifications as: "A new and improved method 
of and means for simultaneously recording and reproducing movements and 

His complete specification was accepted and a patent, No. 18,057, issued August 
10, 1907, which has often since been described as the "master patent" in the field 
of synchronized sound and movement photography. There certainly has never 
been another patent in this field which has quite compared with this in general 
interest and attention, for it has long been the "best seller" of the British Patent 

It has already gone through seven editions and an eighth is presently in pros- 
pect, so unprecedented has been the demand for this paper with the tremendous 
increase in experimental and research work on the sound-film in recent years. 

To sketch, even in the most cursory fashion, Mr. Lauste's later experiments is 
difficult within the limits of this article. Until 1910 he devoted most of his efforts 
to obtaining adequate results in sound recording and reproduction. He had, of 
course, no amplification. 

He experimented with and devised various types of mechanical and optical 
slits and lighting means. The grate light valves he first made for recording were 
unsatisfactory because of the inertia of the mechanical slit used. His limited 
mechanical equipment made it impossible for him to make a slit of this type suf- 
ficiently narrow. 

He used an oscillating mirror with good results, but eventually found this also 
impracticable because the vibrations of the camera interfered with the light waves 
and distorted them. His ultimate sound gate, which embodied a vibrating dia- 
magnetic wire (silicon) acting between the poles of two strong magnets, was en- 
tirely successful. He devised this early in the year 1910. 

In this year also, he paid his first visit to Ernst Ruhmer, the eminent German 
experimenter, in Berlin. It is generally recognized now that these two pioneers, 
a Frenchman and a German, laid down the fundamental theories for photographic 
sound recording and reproduction. They collaborated and exchanged notes on 
their experiments until 1913, the year in which Ruhmer died, and for a time con- 
sidered combining their research activities. 

In 1910 Mr. Lauste first photographed sound and scene on the same film at his 
Brixton, London, studio. Between that date and 1914 he photographed many 
thousand feet of sound pictures. He came to America for a short visit in 1911, 

Jan., 1931] 



with the idea of interesting capital, but was recalled to England too soon for him 
to make any definite arrangements. 

In his short stay in America in the Spring of 1911 he demonstrated his sound 
camera-projector to a number of people and photographed at least one short 
length picture, recording sound and scene. This, doubtless, may properly be de- 
scribed as the first true sound picture to be taken in America. 

In 1912 Mr. Lauste, having sufficiently perfected his recording and reproducing 
systems, began experiments to devise an amplifier for his sound films. But for the 
fact that his capital was limited and the later interruption of the war, it is quite 
possible that the sound picture might have made its public appearance at least a 
decade before its commercial possibilities were demonstrated by means of the 
sound amplifying system developed by the Bell Telephone engineers. 

The fact that Mr. Lauste never succeeded in making his sound processes com- 
mercial or profiting from them, will have no bearing on the measure of fame which 
future film historians will accord him. 

There can be no doubt but that he was the first to record sound and scene upon 
the same film and to reproduce it, and the importance of his researches and early 
experiments will become increasingly apparent with the passing of the years. 


In a brief historical report, such as follows, it is difficult to do justice to the 
colorful career of Jean Acme LeRoy, projection pioneer, whose experimental 
work and invention is the subject of this article. It is a constant temptation 
to turn aside from the cold consideration of his work to tell something of the 
man himself, his struggles, and disappointments, but these matters have no 
place here. 

LeRoy's claim has been that he was the first to commercially show motion 
pictures on the screen, using a projection machine which he had devised. Pre- 
viously, motion pictures had only been viewed through an aperture by a single 
individual at a time. LeRoy first made it possible for many to see the same pic- 
ture simultaneously. 

Nearly a year ago the Society took these claims under consideration and last 
Spring a report was made by the Historical Committee after a careful investiga- 
tion of the available records, of which this article is the substance. Much testi- 
mony in affidavit form was examined, living eye witnesses interviewed, and other 
corroboratory evidence considered before the report of the Historical Committee 
was prepared. All of it bore out the contention, which at first had occasioned 
some doubt and surprise because of the generally accepted idea that commercial 
motion picture projection did not exist in the art until some time in the year 1895, 
that LeRoy had succeeded in accomplishing it a full year previously. 

That the LeRoy projector was never patented or commercialized, in the sense 
that its inventor sought to standardize his invention, and manufacture or intro- 

* A contribution of the Historical Committee, prepared by Merritt Crawford. 


duce it for the use of others than himself, is conceded by LeRoy. In the strictest 
sense, therefore, it cannot be said to have exercised any considerable influence 
upon the development of the early art. 

LeRoy, the showman, used his machine for his own purposes in earning a 
living. He did not regard it then as an invention, but merely as a novelty, an 
added feature for an entertainment program. He made no pictures himself, 
but projected the subjects of others, mostly Edison kinetoscope films, from Febru- 
ary 5, 1894, the date of his first public showing, until the summer of 1897. 

So his "Marvelous Cinematographe," as he described his early projector, cannot 
be said to have contributed in an important way to the motion picture's growth. 

Nevertheless because of the early date of its disclosure, the fact that certain 
features of LeRoy's machine played a part in some of the important patent litiga- 
tion which marked the first two decades of the industry's development, and be- 
cause it anticipated in many essential features the screen machines which later 
were destined to popularize the art, LeRoy's invention possesses a definite his- 
torical interest. 

To sketch briefly LeRoy's background, he was born February 5, 1854, near 
Bedford, Kentucky. He came to New York, while still a youth, and was ap- 
prenticed to one Thwaites, a famous photographer of the pre-Civil War period, 
whose studio was then at No. 1 Chambers Street, New York City. 

In 1876 he posed two dancers, photographing the poses in series, taking over 
two hundred plates. Then he devised an apparatus, using lantern slides, which 
successfully projected pictures on the screen and in a crude way created the 
illusion of motion. 

The device was too clumsy and costly for commercial use, and the rattle of the 
glass slides distracted the attention of the audience, but the apparatus embodied 
a number of the basic principles that remain today in the motion picture pro- 
jector, such as an obscurating shutter (oscillating, not rotary), an intermittent 
feeding mechanism, an illuminant, and lens. 

From about 1880 to 1887 LeRoy was employed by a firm of traveling view 
photographers and on returning to New York worked for various leading photo- 
graphic studios. In 1887 or 1888 he took up his experimental work again, 
but his experience with his glass plate projector had convinced him that until 
some flexible material could be substituted for glass little progress could be made 
toward obtaining successful animated photography. 

As all the world now knows, it was during this period (between 1886 and 1891) 
that the cinematic art was to have its inception in the inventions and discoveries 
of Dr. Marey, Friese-Greene, Goodwin, Edison, Eastman, and others, in the crea- 
tion of the film and camera apparatus, which made the motion picture possible. 

LeRoy, who kept abreast of developments in his special field, knew something 
of the advances which were being made in the direction of animated photography. 
Early in 1893 he obtained by chance some film made by Wordsworth Donisthorpe, 
a well-known British experimenter. It was unperforated, but the views it showed 
in series of a London street scene gave LeRoy an idea. 

The film, itself, probably manufactured by Thomas H. Blair & Co., then the 
leading British camera supply house, was the first that LeRoy had ever seen, al- 
though he had been aware that sensitized celluloid sheets had been manufac- 
tured commercially by Carbutt and others for several years previously. 

Jan., 1931] COMMITTEE REPORTS 111 

With the memories of his old glass plate projector before him, LeRoy set to work 
to devise a machine suitable to project the Donisthorpe film and late in 1893 he 
completed his first model. 

The apparatus was very crude, being constructed mostly of wood. Friction 
rollers were used for feeding and intermittent rollers to obtain stop -motion. The 
results he secured were sufficient to encourage him, but he realized that with the 
imperfection of the film stock at that time and the difficulties of keeping the pic- 
tures in frame, the friction method could not be made practicable without much 
further experiment. 

Meanwhile, the kinetoscope of Mr. Edison, which had lately appeared, was 
beginning to make film history. Raff and Gammon, Edison's distributing agents, 
held an exhibition of the novel coin-operated motion picture machines at the 
Grand Central Palace in December, 1893, and it was here that LeRoy secured the 
solution of his problem for making a practical projecting device. 

As every one knows the kinetoscope used film of the present-day standard, with 
four perforations on each side of the image and LeRoy instantly realized that it 
was far better adapted for projection than the friction method. The Edison 
machine also assured him of a supply of motion picture subjects-, a matter which 
had previously given him much concern, as he had had no definite source of sup- 
ply for his projector. And without film, of course, it was quite useless. 

To complete his invention now required only the substitution of sprocket roller 
for the friction roller, but LeRoy also made many other improvements and, in 
fact, rebuilt his frictional machine almost in entirety. The new machine was 
completed, according to the testimony, on February 3, 1894. 

Two days later, in the showroom of Riley Bros.' optical shop, at No. 16 Beek- 
man Street, New York City, two Edison kinetoscope films were projected before 
an audience of about twenty -five people, mostly booking agents and theatrical 
folk. It is contended, and there has been no evidence developed to contradict 
it, that this was the first time, in America, at least, that a motion picture on cellu- 
loid film was shown publicly on the screen by means of a projection machine. 

All motion pictures shown previously, as far as the records indicate, had either 
been imperfectly projected with a camera for experimental purposes or had been 
shown through an aperture to a single individual at a time, and not to an assembly 
upon a screen. 

This date is substantiated, as previously mentioned, by many of the individuals 
present on that memorable occasion in screen history, in affidavits and by personal 
testimony. The writer has personally interviewed several of those, who are still 
living, and there seems to be no question, but that February 5, 1894, will go down 
in motion picture history as the established date for the first screen show. 

As it was not for a considerable period thereafter, that any other projection 
machines were publicly disclosed, according to the authoritative history by Mr. 
Terry Ramsaye, "A Million and One Nights," which assigns to the year 1895 the 
earliest appearance of any of them, LeRoy 's "Marvelous Cinematographe" 
must be given the historical distinction of being the pioneer screen machine. 

The pictures screened by LeRoy at this first showing in Riley Bros.' establish- 
ment were the Execution of Mary Queen of Scots and Washing the Baby, two 
well-known early Edison subjects. Following the exhibition LeRoy explained 


to those present where his films originated and stated also that he hoped to secure 
others from foreign makers like Donisthorpe. 

Necessarily, because of the short length of his entertainment (the films 
shown took about two minutes to run off), he was not enabled immediately to re- 
ceive any theatrical bookings. There was also probably a question in the minds 
of his audience as to the certainty of his obtaining a future steady supply of screen 
material, although they were much impressed by the exhibition itself. 

LeRoy did, however, receive numerous single engagements and in ensuing 
months gave many exhibitions at clubs, social and church organizations, and 
private entertainments with his screen machine. Among others in the Spring 
of 1894 were engagements at the Bijou Theater and Verona Hall in Brooklyn. 

LeRoy's "pictures in life motion" were principally used as a "filler" on the 
Sunday evening entertainment programs of the period. Among the pictures he 
showed at this time were the famous Leigh Sisters in The Umbrella Dance 
and The Trilby Dance, the Serpentine Dance by Annabelle, and Hoyt's Milk 
White Flag, all of them Edison kinetoscope subjects. 

From the Spring of 1894 until July, 1897, he gave numerous exhibitions in many 
states, using the same projector, but showing a great diversified program of films. 
He has probably the distinction of taking out the first motion picture "road- 
show," though the mishaps of that adventure would require a separate article to 
narrate, and there is in existence an ancient handbill, which attests that on Wash- 
ington's Birthday, 1895, LeRoy's troupe of featured players and the "Marvelous 
Cinematographe" with "pictures in life motion," entertained the citizens pf 
Clinton, New Jersey. 

It was not until 1897 that it occurred to LeRoy that he ought to patent his 
projector, as by that time many other machines had appeared, the marvelous in- 
dustrial development of the industry had begun, and he came to realize, probably 
for the first time, the possibilities of his invention. 

He then consulted a patent attorney and was frankly told that he was just about 
one year too late, the two years' grace accorded the inventor by law to disclose 
his invention having expired February, 1896. 

Of LeRoy's later contributions to the art and his numerous patented improve- 
ments on the projector, which related principally to the elimination of the first 
hazard and the prevention of eye-strain, etc., I shall make no attempt to enu- 
merate here. I would like to record, however, that it was LeRoy who devised the 
projection booth for fire protection, which the National Board of Fire Under- 
writers adopted as the standard back in 1907, and that LeRoy refused to patent 
it, though it had many patentable features, on the ground that public Safety re- 
quired that means for fire protection should be free and unhampered for all. 

During the battle between the so-called "independents" and the Motion Pic- 
ture Patents Company, beginning in the year 1909, LeRoy also played an im- 
portant part. His projector helped to establish the fact that the essential inven- 
tions for animated projection were in the public domain, by reason of his use of 
his projector, which thus constituted "prior art." In this he was materially aided 
by Mr. Alfred H. Saunders, then editor of Moving Picture News, the forerunner of 
today's Motion Picture News, who published pictures of LeRoy's machine and 
a full description of it and its history in his publication, August 12, 1911. 

Until some two years ago LeRoy was far more active than many younger men 

Jan., 1931] COMMITTEE REPORTS 113 

in the industry. Like many other inventors his life has been one of hardship and 
disillusionment. But his keen interest in all matters having to do with the art 
has never wavered. And his collection of early films and historical memorabilia 
of the motion picture's growth has probably not its equal in America. 

On August 28, 1928, he was stricken, while working in his shop, then in West 
44th Street, New York, and since that time he has been confined to his home, par- 
tially paralyzed. His mind, however, is fully active and his memory of dates and 
events in film history remarkable. He is proudest, however, of being a "pioneer." 
and of having played some part in the motion picture's beginnings. 


The following abstracts are published by courtesy of the Eastman Kodak Company, 
publishers of the Monthly A bstract Bulletin of the Kodak Research Laboratories. 

Profits of American Studios. W. H. GORDON. Brit. J. Phot., 77, July 25,1930, 
p. 446. This article gives study of working expenses and profits of photographers' 
businesses in the United States for the year 1928 as reported by a business research 
bureau of an American university. Of the sixty-seven professional firms studied, 
thirty-three had an operating profit above the average of 10.5 per cent. The 
total average business done amounted to approximately $14,500. Of this 
average amount received, 26.3 per cent represented cost of materials, working 
expenses 63.2 per cent, and average profit 10.5 per cent. Detailed analysis is 
given of the working expense item, and conclusions are drawn from the entire 
report. A need is emphasized for photographers to gain more accurate knowl- 
edge of business methods, particularly of the use of budget control systems. 

Soviet Hollywood. Kinemat. Weekly, 162, Aug. 21, 1930, p. 24. It is stated 
that work on the Moscow motion picture film plant has been intensified so that 
it will be ready for production early in 1931 instead of 1933 as originally intended. 
Two systems of sound-on-film recording are to be used, the inventors being 
Shorin and Tager. 

Expansion of Amateur Cinematography in America. K. A. BARLEBEN. 
Phot. Korr., 66, May, 1930, p. 128. The early systems, of which the Movette 
was perhaps the most important, were not commercially successful and dis- 
appeared, but they have led to the now established systems. 

Cinematography in the Photographic Studio. A, JASCHKE. Photographe, 17, 
June 5, 1930, p. 233. A motion picture camera is recommended for taking pictures 
of infants, dancers, and like subjects. Finished pictures are made either by direct 
enlargement preferably on bromide paper, or indirectly by means of a master 
negative. The equipment necessary for this work is described. 

Sound Film Patent Situation. P. HATSCHEK. Kinotechnik, 11, Nov. 5, 1929, 
p. 570. German patents are reviewed covering the different elements in the re- 
cording and reproduction of sound in synchronism with pictures. The com- 
ments are critical as to the covering force of the individual patents. 

Dividing Screen. Kinemat. Weekly, 163, Sept. 25, 1930, p. 67; Bioscope (Mod. 
Cinema Technique), 85, Oct. 1, 1930, p. ii. Mention is made of a Morris "Di- 
viding" screen in use at the Scala Theater, Nottingham. The image luminosity 
is said to be doubled by the use of a thin muslin screen used between the acous- 
tically transparent "Transvox" screen and the felting. (Presumably the felting 
referred to is placed behind the loud speakers to prevent reverberations from the 
rear, while the muslin is placed between the loud speakers and the screen. Ab- 

Revolutionary New Set. Bioscope (Mod. Cinema Technique), 85, Oct. 1, 


1930, p. v. A new sound reproducing equipment, the Brown Magnetorge, is 
being marketed by Magnetic Talking Pictures, Ltd. Transmission is by means 
of a "magnetic torque motor," a principle said to be novel to cinema work. A 
special optical system is employed so that the light, after passing through the 
sound track, is reflected to a photo-electric cell placed centrally between the two 
projectors. Brown amplifiers and loud speakers are used. The complete equip- 
ment for sound-on-film and disk costs $2750. 

Selenium for Talkies. R. H. CRICKS. Kinemat. Weekly, 163, Sept. 11, 1930, 
p. 55. The Automatic Light Control Company, Ltd., has developed an im- 
proved form of selenium cell. A brief description is given of the method whereby 
selenium is deposited on a glass plate so as to give a very wide short current path 
of small internal resistance. Tests have shown that the cell is not susceptible 
to fatigue or temperature changes to any measurable extent, and that the time 
lag can be corrected by an amplifier with a suitable inductive circuit. The cell 
is not sensitive to color changes. 

R. C. A. Aids the Hard-of-Hearing Fan. Ex. Daily Rev., 28, Sept. 20, 1930, 
p. 18. Persons whose hearing is defective are supplied with direct telephone 
connection to the amplifier. A receiver is held to the ear by means of a lorgnette 
handle, and a cord extends to a plug for a receptacle on the arm of the seat. 
The volume of sound can be controlled to suit the user. 

New Continuous Printer. L. EVELEIGH. Kinemat. Weekly, 162, Aug. 21, 1930. 
p. 65. The Vinten continuous printer for sound films is described. Contact is 
established by a curved gate with a flattened aperture through which the films 
are pulled at the correct tension by a specially designed sprocket wheel connected 
by a spring coupling to a flywheel on the same spindle. Uneven running of the 
sprocket is thus damped by the inertia of the flywheel. A universal fitting 
allows for the insertion of any type of printing lamp for the picture, while a 12 
volt lamp is used for the sound track, provided with an ammeter and a control. 
The speed of printing is stated to be 120 feet per minute, and arrangement is 
made whereby batteries of printers can be placed in line, the negative running 
directly from one printer to the next, thus making any number of prints with 
only one final take-up. A brief description is given of the novel automatic light 
change incorporated. This is controlled by a number of circular disks mounted 
on a spindle with friction clutches. Normally, the disks are held stationary, 
slipping on their axle while the spindle rotates. By means of electromagnetic 
releases operated by a chart, any one of the disks is released and rotates with 
the spindle to make contact and give a predetermined exposure. When the 
exposure is to be altered, the release of another disk moves the contact block which 
has been engaging the first disk, so that it completes its rotation into its original 

Some Experiments in Mobile Color. G. A. SHOOK. /. Opt. Soc. Amer., 20, 
June, 1930, p. 35. A convenient "organ" for producing lights varying in form and 
color is described. Unlike the Clavilux which utilizes a large number of specially 
constructed lamps, this new instrument has a single light source and three rotating 
disks on which are placed the various optical devices and colored filters for pro- 
ducing the mobile light forms. The instrument readily lends itself to automatic 

Devices for Silencing Cameras. Ex. Herald-World, 100, Sept. 13, 20, 1930, 

1 1 6 ABSTRACTS [ J. S. M. P. E. 

p. 48. A report is given of a subcommittee of the Academy of Motion Picture 
Arts and Sciences on twenty-one devices used by various cameramen for silencing 
sound cameras for standard film. Sources of noises in cameras are outlined. 
If carefully serviced and covered with a good housing, the average camera operates 
at a sound level 6 to 10 db. less than whispering at 6 feet from the microphone. 
Sound is propagated through insulated structures by transmission, diaphragm 
action, and leakage. Details are given of the methods of measurement and of 
the exact type of construction used for different cameras. Some of the housings 
are water-tight and air-tight. 

Rome's New Talkie Studios. Kinemat. Weekly, 163, Sept. 18, 1930, p. 63. 
The Cines Pittaluga studios at Rome have been reequipped for the production 
of sound pictures. Moviola and Friess outfits are provided for the examination 
of the sound tracks and films, copies of which can be developed in rooms attached 
to each studio. RCA sound recording equipment is installed, and Vint en 
printers are to be employed. Some details are given of the available lighting 

New Pathe-Cinema Studios. Kinemat. Weekly, 162, Aug. 21, 1930, p. 53. 
The Pathe studios in Paris and at Joinville-le-Pont have been rebuilt and re- 
equipped. RCA Photophone sound equipment is installed both in the form 
of fixed outfits and in three mobile trucks. Dimensions are given of the six 
separate studios, some of which are fitted with baths and floor traps. Current 
at 120 volts is available up to 10,000 amperes, and details are given of the arc 
and incandescent lighting with which the studios are furnished. Workshops, 
laboratories, theaters, stores, garages, and a restaurant complete what are said 
to be the most practical and complete film studios in the world. 

Parallax Panoramagrams Made with a Large Diameter Lens. H. E. IVES. 
/. Opt. Soc. Amer., 20, June, 1930, p. 332. A description of a method used in 
making pictures showing stereoscopic relief is given in which the moving lens 
usually employed has been replaced by a stationary lens -of an aperture large 
enough to cover the field traversed by the moving lens. Among other advantages 
the exposure time required in making relief pictures is considerably shortened 
by the use of this new system. 

Progress of Air Photography. F. E. CHASEMORE. Brit. J. Phot., 77, Aug. 22, 
1930, p. 509. The cameras used in aerial surveys in 1924 and 1928 are described 
and compared. The modern air camera is electrically operated and uses pan- 
chromatic roll film in either of two lengths, one for 50 exposures and another for 
100 exposures. At the side of each picture there are also automatically photo- 
graphed data such as height and time at which photograph was taken, etc. 
When started, the camera automatically takes a series of photographs at the 
required time interval until switched off again. The driving power is a small 
electric motor working from 12 volt accumulators. A fixed slit focal plane 
shutter gives an exposure time of l /w seconds at a full aperture of //4.5, varia- 
tions in exposure being obtained by adjustment of the aperture. 

Jan., 1931] ABSTRACTS 117 


1,780,969. E. BRUNNER. A process and apparatus for producing artistic 
designs. This is a machine for producing kaleidoscopic images of one or more 
negatives. An optical system with lenses and reflectors is employed for pro- 
ducing a real image before a mirror system and then for projecting kaleidoscopic 
pictures from the mirror system to a screen. Mobile color effects of changing 
design may be thus produced. 

1,788,139. R. JOHN. A positive motion picture film capable of use for 
enlarged projection may be made in accordance with this patent by producing 
images of coloring matter applied by transfer. An exposed master positive which 
has the character of absorbing an aqueous dye solution or retaining greasy ink 
corresponding to light and shadows is made photographically. This film is 
charged with color and the color is transferred to a support while retaining the 
proper relationship between film perforations and frame lines for the different 
picture areas of the film. The cost is said to be less than photographic copies 
when this process is employed. 

1,775,610. A. WEISS. This patent relates to a film reel for motion pictures 
having an octagonal opening to engage a film supporting shaft. The shaft may 
extend through the reel up to one flange which is provided with a similar shaped 
opening of a different size. The object is to insure the proper positioning of the 
reel on the supporting shaft and the supporting shaft may be of various forms 
in cross-section such as round, square, triangular, or octagonal. 

1,778,635. C. L. ADISLER. A simple type of support for projecting machines 
in which one pair of legs is movably mounted with respect to another pair of 
legs. The second mentioned legs carry a supporting casting having a bearing 
on which a top is pivotally carried. This top may be adjusted angularly about 
this pivot by means of a worm and worm wheel and the top is counter-balanced 
by a spring to insure ease and smoothness of movement. 

1,783,045. KELLOGG. Contact film printer. This machine is designed for 
moving a plurality of films through a curved path past a printing light. The 
path may be curved more or less so that suitable adjustment may be made to 
care for any deviation in the length of a film from a standard, such deviations 
occurring from shrinkage, expansion, and sometimes from the age of a film. 
The adjustment for altering the curved film path may be automatically or 
manually controlled. 

1,776,637. J. OSTERMEIER. A flashlight designed particularly for photo- 
graphic purposes which will eliminate most of the noise and smoke usually ac- 
companying a flash of the usual type. The lamp is similar in shape to an elec- 
tric light bulb, but contains thin metallic foil, preferably aluminum, hi oxygen 
and an igniting wire. By making the circuit a flash is produced without smoke 
or dust and with only a very little noise. The combustion of the foil does not 
alter the pressure in the bulb sufficiently to break the glass. Only a low voltage 
is necessary to ignite the foil. A flashlight battery may be used for this purpose 
if desired. 

1,780,945. A. SAGIER. This relates to a film frame for a motion picture pro- 
jector in which a film guideway of two relatively movable plates is provided. 
The plates facing the objective may be moved by a handle near the objective 

118 ABSTRACTS [J. S. M. p. E. 

for framing and this plate is resiliency mounted on a second supporting plate 
carrying the objective. 

1,777,419. O. A. Ross. Focus and finding apparatus for motion picture 
cameras. This camera is equipped with an optical system reflecting and focusing 
an image from the objective upon a viewing screen intermittently, and in timed 
relation to taking pictures. Thus an operator can view action through the 
finder and focus it at the same time. 

1,799,653. E. N. BALL. A sound insulated camera is made by building up 
sound proof walls around parts of the camera and film reels. The sound proof 
walls are provided with suitable doors to give access to necessary camera parts, 
and with a window to see through the walls. The housing is built up from a 
tripod head and particularly guards a sound recording chamber from the noise 
of the camera mechanism. 

1,776,049. E. I. SPONABLE. This patent relates to the splicing of sound 
records. To overcome the unpleasant sudden change of sound records where 
films are spliced together a small diamond or arcuate shaped aperture may be 
cut from the film through the spliced sound record. This leaves all but a narrow 
portion of the splice intact so that it does not materially weaken the splice. 

1,781,053. R. E. DEBAULE. Illuminating system. This system includes a 
lamp and reflector assembly. An incandescent lamp is illustrated as having the 
filaments to one side of the center of the bulb, which may be mounted between 
two adjustable, spaced reflectors, one in front of the lamp and the other behind 
the lamp. Condensing lenses are supported in brackets extending through a 
central aperture in the front reflector and are in axial alignment with the fila- 
ments of the lamp. The lamp and reflector supports permit accurate focusing. 
' 1,777,682. E. I. SPONABLE. Combined sound and motion picture camera. 
To dampen mechanical impulses in a camera for taking sound and picture records 
a yielding guiding connection is provided between the film sprocket and the shutter 
shaft. This guide may include a plurality of springs, each having one end con- 
nected to a flywheel, and each having the other end connected to one of a series 
of radial posts carried by a rotating member so that the drive is through the 
plurality of springs. 

1,777,828. LEE DEFOREST. For sound and picture photography this patent 
proposes the use of two cameras, one for the sound record and the other for the 
picture record. Each of these cameras may be driven by a synchronous motor 
so that the sound and picture records may be made simultaneously with the 
cameras which may be spaced at different distances from the scene. These 
records may then be printed on a single film, using the desired portion of each 
film for a completed sound and picture record. 

1,780,585. A. FRIED. A camera support permitting a camera to be mounted 
thereon and arranged to facilitate turning the camera on a horizontal and on a 
vertical axis. To insure smoothness and freedom from "chatter," a gear train 
is arranged to govern the movement about each axis. Each gear train ter- 
minates in a relatively heavy flywheel which limits the speed of the turning or 
panoraming movement. A handle projects to one side of the device for con- 
trolling the desired camera movement. 

1,781,501. E. O. ORD. An optical system for use with camera objectives for 
producing humorous effects. Pairs of prisms are spaced angularly with respect 

Jan., 1931] ABSTRACTS 119 

to each other and may be rotated about the axis of the optical system. Parallel- 
izing lenses a negative and a positive lens are mounted to pass light through 
the prisms. This system permits accurate focusing and is said to give critically 
sharp pictures. 

1,781,923. F. HIRSCH. A shutter for motion picture apparatus mounted 
on the front of an objective formed of a pair of relatively adjustable fan shaped 
blades. These blades are operable by a cam and linkage back and forth across 
the objective to make successive exposures. 

1,799,468. E. GOLDBERG AND O. FISHER. Cinematographic camera. This 
shows a spring driven motion picture camera equipped with two counters to 
indicate units of exposed film and a stop mechanism which is actuated after a 
desired length of film has been exposed. The spring energ}' is never totally 
expended as the stop will always function before the spring is unwound. This 
exposes all the frames equally before the spring grows weak. 



J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio. 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada. 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y- 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio. 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 
Los Angeles, Calif. 

P. MOLE, Mole-Richardson, Inc., 941 N. Sycamore Ave., Hollywood, Calif. 
M. W. PALMER, Paramount Publix Corp., 35-11, 35th Ave., Long Island City, 

N. Y. 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio. 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 




(The completed list of committees will be published in a later issue.) 


W. V. D. KELLEY, Chairman 




W. C. KUNZMANN, Chairman 



C. L. GREGORY, Chairman 




Membership and Subscription 
H. T. COWLING, Chairman 






O. M. GLUNT, Chairman 







G. E. MATTHEWS, Chairman 





W. WHITMORE, Chairman 




H. B. SANTEE, Chairman 






Standards and Nomenclature 
A. C. HARDY, Chairman 






Studio Lighting 
M. W. PALMER, Chairman 



Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 

M. W. PALMER, Chairman . M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

P. MOLE, Chairman C. DUNNING, Manager 

G. F. RACKETT, Sec.-Treas. E. HUSE, Manager 


Brewster, P. D.: Born January, 1886, New York, N. Y. Graduate in Engi- 
neering, Cornell University, 1906. Has been engaged in work on color 
photography from that time to date; President of the Brewster Color Film 

Carrigan, John Beardslee: Born February 13, 1897, Port Angeles, Washing- 
ton. A.B., University of Washington, 1917. Ensign, U. S. Navy, 1918-1919. 
National Recreation Association, 1919-1926, doing publicity, advertising, and 
finance work, including motion picture production. Editor, Movie Makers, 1926 
to date. 

Crabtree, John I.: Born March 27, 1891, at Clay ton-le- Moors, Lancashire, 
England; educated at Victoria University, Manchester, England, graduating 
with the degree of M.Sc. Entered Research Laboratories of Eastman Kodak 
Company in 1913 and since 1917 has been in charge of the departments of Photo- 
graphic Chemistry and Motion Picture Film Developing. 1929 Assistant 
Superintendent, Kodak Park Works. 

Member of the American Chemical Society, Optical Society of America, and 
fellow of the Royal Photographic Society and the Institute of Chemistry of Great 
Britain and Ireland. Extensive publications on photography and motion picture 
work. In 1926 awarded the Progress Medal of the French Photographic Society. 

Elected President of the Society of Motion Picture Engineers, Oct., 1929. 

Downes, A. C.: Born February 26, 1882, Ipswich, Mass. Degree of B.S. from 
Massachusetts Institute of Technology in 1904. 1904-1905 with Hartford 
Laboratory Company. 1905 to date with National Carbon Company. Member 
of the American Chemical Society, Illuminating Engineering Society. 

Dreher, Carl: Graduated from the College of the City of New York, 1917. 
From 1917 to 1922 has been associated with the Marconi Wireless Telegraph 
Company of America, the General Electric Company, the Radio Corporation of 
America, the National Broadcasting Company, RCA Photophone, Inc., and 
RKO Studios, Inc. From 1923 to 1927, engineer-in-charge of Stations WJZ 
and WJY of the Radio Corporation of America. From 1927 to 1928 was staff 
engineer of the National Broadcasting Company; director of the Radio Club of 
America. From 1928 to 1929, chief engineer of RCA Photophone, Inc. Now 
with RKO Studios, Inc., Los Angeles, Calif. Member of the Institute of Radio 

Holslag, Russell Clark: Born October, 1899, Schenectady, N. Y. Engineer 
Corps, U. S. Army, 1917-18. Columbia University, 1921-23. American Trans- 
former Co., 1924. Electric Arc Cutting & Welding Co., 1925-27. Electric Trac- 
tion, New York Central Railroad, 1927-29. Technical Consultant, Amateur 
Cinema League, since 1929. Technical Editor, Movie Makers, 1929 to date. 
Instructor, motion picture photography and technic for the non-professional, 
Brooklyn Institute of Arts and Sciences, 1930. 

Jones, W. C.: Born May 15, 1891, Colorado Springs, Colorado. Graduated 



from Colorado College with degree of B.S. in E.E., 1913. 1914 Western Elec- 
tric Company. 1917 associated with a group investigating devices for submarine 
detection for a special board of the Navy. 1918 technical staff of Engineering 
Department of Western Electric Co. 1925 Bell Telephone Laboratories. Now 
in charge of development of instruments for telephone use. Member of the 
American Institute of Electrical Engineers. Fellow of the Acoustical Society of 

Joy, D. B.: Born September 4, 1901, Marshfield, Mass. Degree of B.S. from 
Massachusetts Institute of Technology in 1923. Associated with the National 
Carbon Company. Member American Chemical Society. 

Lewin, George: Born July 27, 1903. Graduated in Electrical Engineering, 
Cooper Union Institute of Technology. Recording Engineer, Paramount Publix 
Corp., May, 1928, to date. 

Little, William F.: Born October 4, 1880, Philadelphia, Pa. Received B.S. 
degree in 1903 and M.S. degree in 1906 from Rutgers College. Associated with 
Electrical Testing Laboratories in charge of photometric measurements, 1906 to 
to date. Member of Illuminating Engineering Society, International Commission 
on Illumination, American Society for Testing Materials, and Optical Society of 

Marsh, William: Born November 3, 1884, in Kilkenny, Ireland. Attended 
National Academy, London, England. Served in British Army in Boer War and 
in India from 1904 to 1911. Served in U. S. Army from 1912 to 1914. Bausch & 
Lomb Optical Company from 1914 to 1926. Eastman Kodak Company, 1926 to 

Miller, Palmer: Bora May 6, 1903, Dewitt, Iowa. B.S. in Chemistry, 
California Institute of .Technology, Pasadena, California, 1924. Technicolor, 
1925-28; General Electric Company, 1928-29; Brewster Color Film Cor- 
poration, 1929-30. 



Twelve months ago the first JOURNAL was published. As was 
written in the January, 1930, issue of the JOURNAL by our President, 
Mr. J. I. Crabtree, the establishment of a monthly JOURNAL had 
long been the dream of the Board of Governors. The possibility of 
transforming the quarterly Transactions into the monthly JOURNAL 
was due to the untiring efforts of our worthy executives and editor pro 
tern, Mr. L. A. Jones. 

The rapid and healthy growth of the Society in regard to number of 
members, and the widening scope of activities of the Society brought 
about this change. However, this very growth placed an undue 
burden upon the men who fostered it, from which it was necessary 
that they be relieved. 

Another milestone in the history of the Society has been passed. 
In order to pave the way for the future growth of the Society, and 
in order to relieve the officers and editor pro tern of the enormous 
amount of work which they had heretofore contributed as a labor of 
love, the Society recently established general offices at 33 West 
42nd Street, New York, N. Y. This address is henceforth to be the 
permanent mailing address of the Society, through which all officers 
and members of the Society may be reached. The offices are also 
the business and editorial headquarters for the JOURNAL. The newly 
appointed Editor-Manager, Mr. Sylvan Harris, is ably assisted by 
S. R. Renwick and P. K. Sleeman. Members are invited to visit 
the new offices and call upon the Editor for any required assistance. 


At a meeting held on December 5th at the New York Studio of the 
Paramount Publix Corporation, Dr. N. M. LaPorte, of the Paramount 
Publix Corporation, spoke on the subject of wide film and projected 
a number of reels made on 65 mm. film. A number of 35 mm. Keller- 
Dorian color films were also projected. 


126 SOCIETY NOTES [J. S. M. P. E. 

The election of officers resulted in a unanimous vote for reelection 
of the present officers who are as follows: 

Chairman M. W. PALMER 

Secretary-Treasurer D. E. HYNDMAN 

Managers i M * C BATSEL 



At a meeting held November 6th at the Webster Hotel, Chicago, 111., 
the following new officers were elected: 

Chairman J. E. JENKINS 

Secretary-Treasurer R. F. MITCHELL 


Final arrangements were made for the December meeting to be 
held at the Enterprise Optical Manufacturing Company. 

Mr. Earl Pearsall, Jr., who has just returned from Hollywood, 
spoke on wide film developments and difficulties encountered in 
current color processes, particularly Multicolor on which Mr. Pearsall 
has been working. 


Your President regrets to announce that at a special meeting 
called by the London Section, December 2nd, it was resolved by a vote 
of 26 to 3 that the London Section pull away from the parent body 
and form an independent technical organization. This action is a 
result of lengthy negotiations which culminated in an ultimatum 
from the chairman of the London Section demanding various con- 
cessions and privileges, including reduced entrance fees, the right of 
the section to appoint Active members, and a non-budgeted expense 
account which the Board of Governors of the parent body could not 

A canvass of the London membership is being made to determine 
if it is the desire of those members who were not present at the De- 
cember 2nd meeting that the Section be continued. 

Jan., 1931] 



The Society regrets to announce the death of Frederick G. Tutton, 
October 18, 1930. 



Agfa Ansco Corporation 

Audio-Cinema, Inc. 
Bausch & Lomb Optical Co. 

Bell & Howell Co. 

Bell Telephone Laboratories, Inc. 

Case Research Laboratory 

Consolidated Film Industries 

DuPont-Pathe" Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theatres Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Pacent Reproducer Corp. 

Paramount-Famous-Lasky Corp. 

RCA Photophone, Inc. 
Technicolor Motion Picture Corp. 

Transactions of the S. M. P. E. 

A limited number of most of the issues of the Transactions is still available. 

These will be sold at the prices listed below. 

Please note that nos. 1, 2, 5, 6, 8, 9, and 10 are out of print 

Orders should be addressed direct to the General Office, at 33 West 42nd Street, 

New York, N. Y. 


























Volume XVI FEBRUARY, 1931 Number 2 



A New Sound Reproducing System for Theaters. .G. PULLER 131 

Improvements in Design of Dynamic Speakers. . I. B. SERGE 144 

Reproducing Sound from Separate Film 148 

Some Applications of the Comparison Microscope in the Film 

Industry O. E. CONKLIN 159 

Some Observations of Stereoscopic Projection . . JOHN B . TAYLOR 1 68 

Methods of Securing a Large Screen 'Picture 174 

Processes of Photography in Natural Colors 


An Entertainment City ALFRED N. GOLDSMITH 220 

Banquet Speeches (Fall 1930 Meeting) 223 

Committee Activities 239 

Abstracts 246 

Patent Abstracts 250 

Book Reviews 252 

Officers 254 

Committees 255 

Contributors to This Issue 259 

Society Notes 260 

Open Forum 264 






Associate Editors 

C. E. K. MEES 


Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members $12.00 per year; to members $9.00 per year; single 
copies $1.50. Order from the Society of Motion Picture Engineers, Inc., 20th and 
Northampton Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 



Summary. This paper describes a system for high quality sound reproduction 
from film in synchronism with the showing of motion pictures in theaters having a 
seating capacity of 1200 or less. A sound reproducing attachment is mounted upon 
each standard picture projector and is belt-driven by a common motor unit. The sound 
reproducing attachment houses a photo-electric cell which converts a light beam inter- 
cepted by the film sound track into electrical energy. Suitable preliminary amplifiers 
mounted upon independent pedestals amplify the output voice frequency energy of 
the photo-electric cell to a level suitable for further amplification by the main amplifiers. 
A control cabinet provides for switching and attenuating the sound circuits before 
being led to the main amplifiers and thence to the loudspeakers. 

The new Western Electric Small Theater Reproducing System 
described in this paper was introduced by Electrical Research Prod- 
ucts, Inc., during July of this year. This system was developed 
by Bell Telephone Laboratories, Inc., and provides for reproducing 
sound from film in synchronism with motion pictures in theaters 
having a seating capacity of 1200 or less. 

The system as a whole includes two reproducing attachments 
which mount on Simplex pedestals of various types and operate in 
connection with Simplex picture projectors. Each combined re- 
producing attachment and projector is driven by a motor unit also 
mounted on the Simplex pedestal. The photo-electric cell output 
of each attachment is supplied to an associated pickup amplifier 
mounted on its own pedestal directly in front of each projector. 
The outputs of the two photo-electric cell amplifiers are switched and 
attenuated by means of a control cabinet, which usually mounts on 
the front wall of the booth and acts as a combination fader, switching 
and signal cabinet. From this cabinet the sound circuit extends 
through the main amplifiers to the loudspeakers. 

Film Reproducing Attachment. The film reproducing attachment 
comprises a unit assembly arranged for mounting upon a standard 
Simplex pedestal of either the L, M, or R type, and provides for 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Bell Telephone Laboratories, New York, N. Y. 




[J. S. M. p. E. 

FIG. 1. Film reproducing attachment mounted on standard 
Simplex type R pedestal. 



FIG. 2. Film reproducing attachment mounted on standard 
Simplex type L pedestal. 



[J. S. M. P. E. 

mounting a Standard or a Super-Simplex projector head and a Sim- 
plex take-up magazine. Fig. 1 shows the attachment mounted on 
the Simplex type R pedestal and Fig. 2 shows the attachment 
mounted on the type L pedestal. 

The operating side of the attachment comprises (a) a lamp com- 
partment, (b) a film compartment, and (c) a photo-electric cell com- 
partment. Fig. 3 shows these three compartments in detail. 

FIG. 3 Lamp, film, and photo-electric cell compartments. 

The lamp compartment contains the exciting lamp for illuminating 
the sound track on the film. The filament of the exciting lamp is a 
horizontal coil producing an intense illumination. It is important 
that the current consumption of this lamp be kept within the proper 
limits as recommended by the instructions. Exceeding the recom- 

Feb., 1931] 



mended current value will materially shorten the normal life of the 
lamp. In order to locate this filament exactly with relation to the 
associated equipment in the film compartment, the lamp is mounted 
in a special bracket which permits it to be adjusted in any direction 
and locked in position. 

The lamp bracket is replaceable as a unit without disturbing the 
adjustment, so that duplicate lamps may be adjusted for position in 
extra brackets and will then be ready for use should a replacement 
become necessary during the showing of a picture. The various 


FIG. 4. Exciter lamp bracket and adjustments. 

adjustments provided are illustrated in Fig. 4, which shows the lamp 
bracket removed from its compartment. 

The film compartment provides for the passage of the film from 
the projector to the take-up magazine. Between the film and the 
sound lamp a lens assembly is provided, consisting of a lens tube 
mounted in a frame that also mounts an aperture plate with polished 
guides. These accurately locate the emulsion side of the film as it 
passes by the lens tube assembly. The lens tube proper contains a 
combination of condenser and objective lenses by means of which 
the light from the exciting lamp is projected in the form of a con- 
centrated beam 0.001 inch wide on the film at the aperture plate. 
It is sealed in its supporting frame after having previously been care- 

136 G. PULLER [J. S. M. P. E. 

fully adjusted to obtain a line of light of the proper width on the 
film. A light beam of greater width would result in suppressing 
the higher frequencies, which are essential to good articulation 
and brilliance in music. An opening in the aperture plate limits 
the length of the light beam to 0.080 inch. 

The lens surfaces should at all times be kept free from oil deposits 
or dirt, as this materially reduces the amount of light transmitted 
to the film, and results in a reduction in volume. To insure smooth 
passage of the film by the light source, the aperture plate should be 
inspected frequently, and any accumulation of dirt or other foreign 
substance adhering to the guide surfaces should be carefully removed. 

A telescoping sound gate with a self-adjusting pressure pad keeps 
the film in proper contact with the aperture plate when the system 
is in operation. The gate is arranged to be opened for threading 
the film by the aperture plate. A loose loop of film is allowed between 
the lower take-up sprocket in the projector mechanism and the point 
where it enters the sound gate, which prevents the irregular move- 
ment of the film in its passage through the projector mechanism 
from affecting the uniform velocity of the film as it passes through 
the sound gate. The sound gate with the lens tube in position can 
be seen in Fig. 3. The film, after leaving the sound gate, passes 
over a sound sprocket which draws the film through the gate at a 
uniform rate. 

The film next passes over a hold-back sprocket before finally 
entering the take-up magazine. A slack of about two sprocket 
holes should be allowed in the film between the sound sprocket and 
the hold-back sprocket, the purpose of which is to prevent any 
uneven pull on the film due to the take-up mechanism from reacting 
on the uniform velocity of the film as it passes over the sound sprocket. 

A film guide roller mounted directly above the sound gate pro- 
vides an adjustable means for guiding the film edgewise through 
the gate and retains the sound track of the film in its proper path 
with respect to the center of the lens tube assembly. Improper ad- 
justment of this guide roller may cause the light beam to intercept 
a portion of the film having no sound track, and in the event of the 
light beam intercepting the sprocket holes serious disturbances in 
the reproduced sound would result. Fig. 5 is a diagrammatic illus- 
tration showing the path of the film through the film compartment. 

The photo-electric cell compartment houses a Western Electric 
photo-electric cell which converts the light beam intercepted by the 

Feb., 1931] 



film sound track into electric energy which is later amplified and 
transformed into audible sound. 

It is, of course, essential that in order to obtain the maximum effi- 
ciency of the photo-electric cell, the active element or cathode of the 



FIG. 5. Diagram of path of film through film compartment. 

cell be directly in line with the light path. This is accomplished 
by supporting the cell at the spherical portion containing the active 
element a method of support which reduces microphonic pickup 
to a minimum and lessens the liability of cell vibration. Micro- 
phonic pickup is further reduced by mounting the cell terminal on 

138 G. PULLER [J. S. M. P. E. 

a cushioned support. This method of supporting the cell also elimi- 
nates the necessity of base terminals at the cell and raises the in- 
sulation resistance to a point where objectionable ground noise is 
eliminated. The photo-electric cell may be seen in its housing by 
referring to Fig. 3. The photo-electric cell terminal block projects 
from the rear of its compartment and is in the form of a sleeve 
through which the lead of the photo-electric cell is brought out, to be 
later soldered to its terminal in the photo-electric cell amplifier. The 




FIG. 6. Driving side of attachment with flywheel removed. 

cell and its terminals are easily accessible through the front of the 
compartment, which is covered by a removable plate. 

The driving side of the attachment provides the bearings for the 
various shafts and also mounts a removable bracket supporting an 
auxiliary gear unit which meshes with the driving gear of the Simplex 
projector mechanism. The projector and its associated gear unit 
are located in relation to the attachment so that in threading the 
machine the accepted standard length of 14V2 inches of film from 
the framed picture to the corresponding sound record at the light 


beam can be employed. Fig. 6 shows the driving side of the attach- 
ment with the flywheel removed. 

The shafts upon which the hold-back sprocket and the sound 
sprocket are mounted are large in diameter and are provided with 
ample bearings, which are lubricated by means of wick-filled chambers 
connected by tubes terminating in a single oil manifold. These 
two shafts, as well as the auxiliary gear unit for driving the Simplex 
projector, are interconnected by means of a simple train of three 
gears, which are the only gears employed in the attachment. The 
auxiliary gear unit is lubricated by means of its own oil cup attached 
to the end of the supporting pilot shaft. 

A large diameter flywheel of considerable mass is rigidly mounted 
on the end of the sound sprocket shaft and is driven from the motor 
pulley through the medium of a pair of round, woven fabric belts 
which run in grooves on the flywheel rim. This type of drive is quiet 
in operation and free from disturbing vibrations. At the same 
time it provides -a very efficient filtering action, resulting in uniform 
rotational velocity of the sound sprocket and, consequently, freedom 
from objectionable flutter disturbances. Uniform film velocity at 
the light beam is further assured through the high degree of pre- 
cision employed in the manufacture of the sound sprocket. 

As an additional precaution against the transmission of any dis- 
turbances to the sound sprocket, the gear which drives the hold-back 
sprocket shaft and the auxiliary projector gear unit is mounted so as to 
float on the sound sprocket shaft. The gear is coupled to the sound 
sprocket shaft by means of a cushioned yoke, which mechanically 
insulates the sound sprocket from any irregularities due to inaccurate 
gear tooth spacing, gear vibrations, or projector load reaction. The 
units making up this cushioning device are illustrated in Fig. 7. 

To facilitate ready removal during shipment and to simplify 
maintenance, the flywheel is held on the tapered and threaded end of 
its shaft by a special nut which also acts as a wheel puller when un- 

A tension pulley for keeping the proper tension on the belt driving 
the take-up reel, is hung from the film reproducing attachment. 
This pulley revolves on an oil-less bearing which requires no lubrica- 
tion. Oil on this type of bearing is detrimental to the free rotation of 
the pulley. 

All parts of the attachment which are subject to wear have been 
made interchangeable and easily replaceable. 



[J. S. M. P. E. 

Motor-Drive Unit. The motor used to drive this equipment is a 
VG H.P. single-phase, squirrel-cage induction motor having a split- 
phase starting winding which is open-circuited by a centrifugally 
operated switch when the motor reaches a speed of approximately 
1200 rpm. This motor normally operates on 110 volts at a fre- 
quency of either 50 or 60 cycles, the normal speeds being approxi- 
mately 1445 and 1740 rpm., respectively. Suitable pulleys are 
provided so that the standard sound picture speed of 90 feet of film 


FIG. 7. Details of cushioned driving gear. 

per minute may be obtained with either of these motor speeds. The 
speed regulation of this motor depends upon the frequency of the 
power supply, which must be held within plus or minus 3 percent 
in order that the absolute pitch of the reproduced sound will be 
within sufficiently close limits. In addition, it is essential that the 
rate of change of frequency of the power supply system should be 
less than 0.2 of 1 percent per second in order to avoid noticeable pitch 
changes. The constant speed characteristics of the motor are 
such that no auxiliary speed control device is necessary. The motor 


is mounted in a rubber cushioned frame, which reduces vibrations 
transmitted to the projector pedestal. Fig. 2 shows this motor drive 
assembled on the Simplex pedestal. 

The bracket which supports the motor is made in the form of a 
shelf and mounts upon the Simplex pedestal. Two independently 
acting tension pulleys mounted on it provide constant tension for 
the belts under all conditions. These pulleys rotate upon oil-less 
bearings which do not require oil for lubrication. 

The fabric belts used are pre-stretched. However, in some cases 
a slight elongation of the belt may be found. In order to com- 
pensate for changes greater than the belt-tightener will accommodate, 
and to provide for various projection angles, the motor may be 
moved back on its bracket. 

Photo-Electric Cell Amplifier. The photo-electric cell pickup am- 
plifier amplifies the output voice frequency energy of the photo-electric 
cell to a level suitable for further amplification by the main amplifiers. 
It comprises a two-stage, transformer-coupled amplifier employing 
two Western Electric No. 239-A vacuum tubes. The amplifier is 
mounted in a self-supporting housing entirely separated from the 
projector proper, thereby preventing any machine vibrations from 
directly setting up objectionable disturbances in this amplifier. 
The amplifier pedestal may be seen by referring to Figs. 1 and 2. 
To further aid in minimizing vibration pickup the amplifier is sus- 
pended by springs in a cradle mounted upon a rubber pad. The 
front of the housing is hinged to give access to the amplifier and 
vacuum tubes. The filament current of the amplifier tubes may be 
observed and adjusted without opening this door. 

The lead from the photo-electric cell compartment to the pickup 
amplifier is carried through an insulating sleeve which enters the 
amplifier housing through an opening in a sliding plate. The close 
proximity of the pickup amplifier to the photo-electric cell provides 
a short, rigid lead between the two, which prevents adverse reaction 
of this lead on the electrical output. 

As it is essential that the lead between the photo-electric cell and 
the pickup amplifier be as short and rigid as possible, this lead is 
first soldered to its proper terminal in the pickup amplifier, after 
which it is pulled almost taut through the insulating sleeve into the 
photo-electric cell compartment, the lead being then cut so as just to 
permit soldering it to the terminal provided for this purpose. 

The height of the pedestal supporting the pickup amplifier is 



[J. S. M. P. E- 

adjustable so that the amplifier may be placed in proper relationship 
to the photo-electric cell compartment on the attachment, as deter- 
mined by the projection angle employed. 

The sliding plate on the amplifier housing, through which the 
photo-electric cell lead enters, may be raised or lowered slightly to take 
care of small, final adjustments in the projection angle. 

Switching and Control Cabinet. The switching and control cabinet 

serves as a combination fader, switch- 
ing, and signal cabinet. The cabinet 
itself is of sheet metal and has perfo- 
rated sides and a hinged cover. On the 
cover are mounted ammeters and rheo- 
stats for indicating and adjusting the 
current supply to the exciting lamps and 
the necessary switches for controlling the 
current to the photo-electric cell ampli- 
fiers. In the cabinet are a volume-con- 
trol potentiometer operated by a shaft 
extending out through both sides of the 
cabinet, and a three-position switch, 
similarly operated, for applying the 
output of either photo-electric cell ampli- 
fier across the potentiometer. The po- 
tentiometer permits adjustment of the 
input level to the main amplifiers in 3 
db. steps. Green and red signal lights 
are provided to indicate to the operator 
the "ready" and the "play" positions, 
respectively, of these circuits. The con- 
trol cabinet is shown in Fig. 8. 

The cabinet is intended to be 
mounted on the front wall of the 
booth so as to be in a convenient and accessible location for one 
operator attending two machines or for two operators stationed 
one at each machine. This location also provides all the operators 
in the booth with a means for inspecting the circuits and 
machines in actual operation. From the cabinet the circuits are 
led to master amplifiers and thence to the loud speaking telephones. 
These units may be any of the usual types, as dictated by the pri- 
mary power and installation requirements. 

FIG. 8. Switch and control 


Flywheel Guard. A guard for the flywheel and driving belts may be 
provided when required. This guard consists of a sheet steel housing 
and is supported on two brackets suitable for any projection angle 
employed. Fig. 2 illustrates this guard in position. 

Flywheel Brake. Under normal conditions the momentum of the 
heavy flywheel pulley causes the machine to continue to run for an 
appreciable time after the power to the motor is shut off. Where 
a shorter stopping period of time is desired a combination brake and 
switch unit is provided. The design of this brake is such that when 
the operating handle is depressed the power is first shut off, then pres- 
sure is exerted through a spring to a brake-shoe applied to the inside 
rim of the flywheel pulley. The use of a spring prevents the pos- 
sibility of stopping the machine too suddenly and damaging the 
mechanism. Raising the handle operates the switch to turn on the 
power and start the motor. Fig. 3 shows an illustration of this 
flywheel brake mounted. 

General. The system in general is of rugged construction, simple 
to operate, and is capable of reproducing sound of high quality and 
free from flutter. The attachment permits the same projection 
angles to be used as are normally obtainable when the standard 
Simplex projector is mounted on the types L, M, or R pedestals. 

While Simplex projectors and pedestals have been referred to 
throughout the text, it is understood that there are certain other 
makes and types of projectors and pedestals with which this system 
may also be associated. 

The especially notable features which have been provided for in 
the attachment are its simplicity, the ready accessibility of the 
essential parts, and the ease with which it may be threaded with film. 


I. B. SERGE** 

Summary. The writer points out that by using a smaller number of reproducing 
units, fewer technical difficulties are involved in sound installations. With this in 
mind, a super-electrodynamic speaker has been designed, paying proper attention to 
the following requirements: (J) high air-gap flux density, (2} size of voice coil, (5) 
material and design of magnetic circuit, (4) design of air-gap face to provide large 
uniform air-gap density, (5) small leakage flux. The acoustical coupling between 
the loudspeaker and the auditorium which it is to serve must be considered in install- 
ing sound equipment, and is a matter upon which the success of the installation 
finally depends. 

During the convention of the Radio Manufacturers Association at 
Atlantic City last June, a meeting was held by the Institute of 
Radio Engineers. A lengthy discussion on the need for better 
sound reproducing units was held. Although many engineers 
are working along new lines in sound reproduction, at the present 
time the dynamic type of sound reproducing unit is used universally. 

The first dynamic reproducers were designed for home use, and 
were capable of giving more sound output than necessary. During 
the past three years, the design of dynamic reproducers for home use 
was characterized by making them smaller and smaller, and today in 
the so-called midget set, the weight of copper is in some cases less 
than one pound. On the other hand, loudspeakers designed for audi- 
torium use were generally similar to those used in the home, with the 
exception that the amounts of copper and iron were increased, afford- 
ing a slight gain in efficiency. This demanded a multiplicity of 
units in auditorium installations, resulting in the involved problem 
of inter-connecting them so as to maintain their efficiency. 

The sound picture industry has come to realize that better record- 
ing and reproducing systems must be developed in order to satisfy 
the theater-going public. In this paper we are particularly interested 
in developments being made to improve the design of the dynamic 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Consulting Engineer, Rochester, N. Y. 


loudspeaker for auditorium or sound picture installations. The 
main points of the present development will be reviewed briefly. 

It should be understood that most acoustic problems are consid- 
ered on the basis of a point source of sound. In actual practice 
where reproducing units are not capable of handling large power 
inputs, the acoustical engineer must employ a number of units, 
properly phased to approximate the results desired. Obviously 
the use of a small number of reproducing units leads to few technical 
difficulties and approaches the ideal of a single point source. Herein 
lies the first problem to develop units having large power ratings 
so that ideal conditions may be approached. To obtain higher 
acoustical levels, the designing engineer turns to the dynamic type 
of loudspeaker. As the power input is increased, the size of the 
moving coil of the unit must also be increased, in order that the 
proper heat radiation and mechanical impedance relations may be 
realized. The moving coil impedance is then chosen to give the 
best conversion efficiency possible. The conversion efficiency 
(the ratio of mechanical watts radiated to electrical watts input) 
varies as the square of the flux density in the air-gap, so that the next 
problem is that of maintaining a high flux density in the air-gap of 
the magnetic circuit. By increasing this density the force acting 
on the cone will increase in direct proportion. This can be done, 
but the design becomes increasingly more expensive as the air-gap 
density is increased. There are several reasons for this: 

First, the flux density in the air-gap is limited by the saturation 
density of the magnetic structure; second, it is often difficult to 
obtain the most suitable materials for this structure; third, in 
many instances the magnetic structure is not so designed that the 
maximum useful flux is obtained in the air-gap for a given total flux 
in the magnetic circuit. In other words, leakage factors are disre- 
garded. The result is that some portion of the magnetic circuit 
becomes saturated. This requires an excessive magnetizing current 
in the field coil to obtain the maximum possible density in the gap. 
Often the desired air-gap density cannot be maintained without sub- 
jecting the field to dangerous temperatures. The designer must then 
pay careful attention to the size of the magnetizing coil, so that the 
core spindle does not become saturated. 

The face of the air-gap must be increased to provide as large 
a uniform-density air-gap as economy permits. Most dynamic 
speakers have too small a face in the air-gap, which results in a 

146 I. B. SERGE [J. S. M. P. E. 

variation of impedance detrimental to the efficiency of conversion. 

The next step is to so choose a set of dimensions that the leakage 
flux will be small. In many dynamic speakers, only about 20 per 
cent of the available flux passes through the air-gap. The remainder 
leaks between the core and pot and the core and pole plate. With 
careful design it is possible to increase the useful flux to a value 
nearly twice as great as this. 

The next step is perhaps the most important, viz., the selection of 
proper magnetic materials. The ideal speaker should have different 
materials for the core head, core spindle, pot, and pole plates. What 
alloys should be used is a matter to be determined both by the elec- 
trical engineer and the metallurgist. Very encouraging results have 
been obtained by the use of special alloys, the magnetic specifications 
of which are generally supplied by the steel manufacturers. 

Finally, the designer must determine the proper number of turns 
and the resistance of the field windings of the speaker unit. Inas- 
much as fewer units are to be used with the improved dynamic 
speaker, greater power dissipation is permissible in the field winding. 
Radiation must be provided for the heat produced. In unusual 
circumstances forced ventilation may have to be resorted to. Me- 
chanical limitations in the design leave a narrow margin for extra 
radiation factors. 

The next question which arises is: will the cone attached to the 
dynamic speaker, made of thin, light materials, withstand the 
high conversion ratio of electrical to mechanical energy? Consider- 
able difficulty has been encountered in the past in properly develop- 
ing the moving coil suspension and the suspension for the cone edge. 
Practical experience has helped overcome these difficulties and it is 
now possible to build cones which will withstand quite high conver- 
sion ratios. 

In the present design it was found that after taking into account 
all the details outlined above, the sensitivity of the speaker was 
increased considerably and a fairly flat frequency characteristic 
was obtained. 

However, the inherent limit of the dynamic speaker cut-off at 
high frequencies is still present. For this reason, special high fre- 
quency units must be produced if it is desired to reproduce frequen- 
cies above 6000 to 6500 cycles per second. A combination of two 
sound reproducing units with their associated filters and separate 
amplifiers will cover the audible range desired. This combination, 


in the opinion of the author, represents the sound picture installation 
of the future. 

The success of the present type of dynamic speaker, as well as those 
to be developed in the future, depends upon the acoustical coupling 
placed between the reproducing unit and the auditorium which it is 
to vserve. The so-called baffle horn is very effective and quite satis- 
factory. However, it is important to understand that each instal- 
lation is a separate problem, as far as dimensions of the coupling 
medium and its shape are concerned. 


MR. COOK: In connection with Mr. Serge's discussion of the power limits of 
a loudspeaker, I would like to mention two considerations which have come to 
the attention of many engineers more forcibly in the last year. One of these 
defects is quite severe. It is often felt desirable to augment the bass response 
of speakers by putting a peak in the bass region. This can be a handicap as 
well as an advantage. If the thickness of the front plate does not permit sufficient 
movement of the cone coil in a region of constant flux density, it is evident that 
the acoustical response will not be proportional to the input. A resonance peak 
in the low frequency region makes this limitation more severe. The second 
cause of distortion which limits the power rating, occurs at the seal of the cone. 
It is desirable to make this seal more flexible, and if this is carried far enough, the 
possibility of having the edge vibrate in what might be called "bell" vibrations, 
is encountered, and the edge is no longer a circle. If the edge seal is cut away 
altogether and the cone allowed to vibrate in free air, the power rating for un- 
distorted output drops very rapidly. Thus it is not permissible to have such a 
seal that the cone can move without some edge restraint and still retain the rating 
obtained when a slight edge restraint is used. 



PRESIDENT CRABTREE: The matter of obtaining a wide screen 
picture and better sound reproduction should be freely discussed 
by our members. To what extent would putting the sound and 
picture on separate films contribute to these ends? There is no 
question that the quality of sound reproduction must be consider- 
ably improved, especially that of music, if the public is to remain 
interested very much longer. The reproduction of speech, I think, 
is quite good, but the quality of music is very poor, in my estimation. 

In the average projector the film is subjected to heat, oil, dirt, 
scratching, and to an intermittent motion, all of which are not con- 
ducive to good sound quality. It will be necessary to treat the 
sound track more carefully in the future if we are going to simulate 
orchestral music with any degree of realism. One way of doing this 
would be to have a separate device for handling the sound track; 
in other words, a separate machine would be required, wherein the 
speed of the film could be much higher than at present, aiding in the 
reproduction of higher frequencies. It would then be a simple matter 
to obtain smooth motion, and the film would not be subjected to dirt 
and heat as in the present projector. These possibilities have been 
pointed out previously at our meetings, but they must not be lost 
sight of. In the future it may be necessary to use multiple sound 
tracks. The Progress Committee reported that in Hollywood sound 
has been reproduced simultaneously from two or more identical 
sound tracks, so that the resultant sound was an integration of the 
individual effects. I cannot help but feel that in the near future 
some one may demonstrate that by utilizing two or more sound tracks 
the entertainment value of the picture can be greatly enhanced, and 
as soon as that is done, the industry will have to consider it very 
seriously. Of course, this is looking several years ahead, but that 
is the duty of this Society. 

The main objection to this method is the possibility of lack of 


synchronism and of mixing up the sound record with the picture re- 
cord, as has been done on occasion with the disk records. How- 
ever, there is not the danger of sudden lack of synchronism, such 
as when the needle jumps out of the groove in a record. The only 
possibility would be a film break, but I haven't seen a film break in a 
theater during the past six months. 

There are other matters, such as extra cost and difficulty of trans- 
portation, but when we remember that to put on a traveling show 
requires a train load of baggage, and to put on a motion picture show 
requires only a few pounds of baggage in the form of film, I don't 
think that the industry should reject a system having ultimate 
possibilities because of a little extra cost of handling. 

There is also the matter of rehearsal. Some theaters advertise a 
big show two or three weeks in advance, and five minutes before the 
show the film is delivered at the projection booth. The projectionists 
have no opportunity to rehearse the film so that if an incorrect package 
is delivered, the show cannot be put on. 

Sufficient time should be allowed in delivering the film for such a 
rehearsal; if this were done I believe the possibilities of getting the 
sound and picture record mixed would be negligible. 

MR. JAMES: While in Chicago, I was fortunate enough to view 
a demonstration of sound on a magnetized metal base. The demon- 
stration was given in the Hart Theater on Hart Street. I was 
skeptical about how long the magnetism would be retained by the 
metal base but was informed that it had been placed on the base three 
years ago and had been run one thousand times. The music was 
beautiful and the speech splendid. I suppose it was a special alloy. 

PRESIDENT CRABTREE : This is an adaptation of the ' ' telegraphone' ' 
which Mr. Taylor discussed at length at our Lake Placid meeting. 

MR. STERN: Through my work in the laboratories I have had 
considerable experience in developing sound tracks, and long ago came 
to the conclusion that the treatment of the sound track positives 
separately from the picture print, as is done in negative recording, 
would have considerable advantages over the present method. Mr. 
Crabtree has pointed out many of these advantages in his introduc- 

This would aid in regaining the lost space that is now used by the 
sound track. Moreover, the sound track requires different develop- 
ment in the positive and negative processes. There are three major 
sound recording systems used by our producing companies: (1) the 


DeForest and Fox-Case recording systems, in which negative stock is 
developed in a borax negative bath for a good average contrast; 
(2) the Western Electric system, in which recording is done on posi- 
tive stock, developed in a soft positive bath for less contrast; (3) 
the RCA method, in which recording is also done on positive stock, 
developed for extreme contrast. By printing these sound tracks 
on the same positive with the picture it is impossible to give the 
desired quality of contrast to both the picture and the sound track. 
As a consequence, the quality of one or the other has to be sacrificed, 
and it is usually the photographic quality of the picture. 

Bearing these facts in mind, and desiring to utilize the entire film 
for the picture, I designed a means of placing the sound track on a 
separate film so that the latter might be utilized in the same pro- 
jection machine with the picture positive. 

First, one sound track is printed on 35 mm. positive film in the 
present-day printing machine. Then, by taking another negative 
sound track and turning the already once printed positive stock 
around and running it backward, another sound record is printed. 
Both sound records are adjacent to the perforations. The positive 
is then developed and dried in standard developing machines, and 
when ready to leave the laboratory is slit into halves, each half ac- 
companying its respective reel of pictures. The halves are wound on 
reels which are wider than the present ones, having in them separat- 
ing metal disks, on one side of which are wound the picture films, 
with the accompanying sound track films on the other side. 

In this case everything is standard picture cameras, recording 
cameras, reproducing machines, and the projection machine with 
the exception of the following minor changes: the upper and lower 
magazines, the two feed sprockets and rollers, and a shift-base for the 
sound reproducing unit are replaced, in order to accommodate both 
sound-on-film and sound-on-separate-film. The same projection 
machine can be used for projecting silent films or sound-on-disk 
films. While discussing this process with producers and engineers 
I gained considerable knowledge of the different viewpoints on pro- 
jecting sound track on separate film. All are agreed that by pro- 
jecting the sound track separately better reproduction is obtained. 
Some prefer a wider sound track; others prefer recording at greater 
speed. Others have doubts as to whether the two films can be kept 
in synchronism or how the two films can be wound at the same time. 
As to synchronizing, the starting point will be marked on both 


films in the same way as it is marked on the sound film of today. 
Each reel of sound film that leaves the laboratory has its footage 
numbers printed on the edge of the film. In case of a break in one 
of the films all that the operator has to do is to note the edge number 
of the picture film that is on the aperture plate; the corresponding 
number on the sound film is then placed under the sound producing 
aperture. In case the film is damaged and a few frames have to be 
cut out, the corresponding frames of the sound records can be cut out ; 
or, better still, the sound track may be left intact, the missing frames 
being replaced with black frames as is done now with sound-on-disk 
films. In case of censorship elimination ; the exact amount of sound 
film is taken out with the picture film, avoiding the jump that is 
noticed where the sound track is printed on the same film. If, in 
the present method we wish to use the base tints, we have to match 
and splice positive stock for the exact length of each color before print- 
ing an impracticable procedure. If this process is adopted beautiful 
base colors and tones can be utilized in the same way as was done 
in the silent pictures. 

Another feature that Mr. Crabtree pointed out is that of record- 
ing sound at greater speed. I advocate a speed of 75 feet per minute 
for photographing and projecting pictures, with a speed of 112V2 or 
even 150 feet per minute for sound track recording, rather than 
reducing by optical printing to the projecting length of the picture. 

MR. TEITEL: Referring to the matter of coloring film or tinting 
intermittent sections of film without coloring the sound track, I 
would like to say that I have designed a machine in which coloring 
members come in contact with the film, instead of the film coming 
in contact with the coloring matter, so that one scene may be black 
and white, one toned, one tinted, another toned and tinted, and an- 
other in full color, all in one continuous operation, without touching 
the sound track. The coloring member comes in contact with the 
film so that it is not necessary to kill colors by having the entire reel 
colored, and so the necessity of cutting and re-splicing various sections 
for colors is avoided. I hope this machine will be ready for demon- 
stration at our Spring meeting. 

MR. OTIS: Multicolor has cooperated with Electrical Research 
Products, Inc., in a series of experiments on the effect of toning the 
sound track red or blue. 

Using the potassium photo-electric cell, the red track could not 
be made to produce as good quality as the blue track; but the blue 


track gave quite satisfactory results. When E. R. P. I. releases 
their new caesium cell it will be possible to not only duplicate, with 
Multicolor blue, the quality of the black and white sound track, but 
also to secure a track producing, by two fader steps, a greater volume 
than the present black and white track. 

PRESIDENT CRABTREE: I think Mr. Jones gave the effect of 
tinting the film with different dyes on the output of a potassium 
cell at one of our recent meetings. Further work could be done on 
the effect of different tones dye tones and organic tones on 

MR. Ross: It seems to us that there are so many advantages in 
recording sound on separate film for exhibition that eventually the 
industry will be forced to it. We call attention that, to properly 
produce the sound effects in Hell's Angels, a separate film having 
two sound tracks is employed. Dramatic critics at S. M. P. E. meet- 
ings have forcibly pointed out the necessity for producing realistic 
"off-stage" effects which now are produced directly rearward of the 
screen. These realistic "off-stage" effects can be accomplished by 
employing separate sound film having a plurality of sound tracks, 
each related to a group of loudspeakers located at points from which 
the sounds are to be produced and which may be at remote portions 
of the stage or auditorium. Another example: When recording 
a plurality of sources of sound, as, for example, a singer's voice and 
musical accompaniment, distortion occurs in recording due to the 
super-imposing of the two sound waves, so that faithfulness in re- 
production during exhibition is lacking. It is therefore advisable 
to record the singer's voice onto one track and the accompani- 
ment onto another track. Another example: Musical accompani- 
ment often attends dialog for emotional effects. When the musical 
selections are super-imposed on the dialog sound track in printing, 
as is the general rule in dubbing, the dialog suffers in faithfulness 
and again it is advisable to record the dialog and musical selec- 
tions on separate sound tracks. 

Any sound that one might wish to produce from points other than 
the immediate foreground depicted on the screen may be handled 
in this manner. Loudspeakers may be placed at remote portions 
of the stage or auditorium. There are decided advantages for this 
arrangement which are quite evident to anyone who has tried it. 

As an example: Some one might be singing in a distant garden, 
in which case a loudspeaker at the rear of the stage (perhaps off 


to one side) would produce the desired "off-stage" effect. It would 
not be difficult to change over present standard 35 mm. projectors 
to handle separate sound films. The present single-reel upper and 
lower magazines can either be converted or replaced by new two- 
reel upper and lower compartments. The sound head could be 
supported between these compartments. The projectors, so altered, 
would not take up any more room than the present sound equipped 

PRESIDENT CRABTREE: It is my understanding that stirring 
music is felt throughout the body, not merely in the ear, so that loud- 
speakers located in the vicinity of the audience might produce such 
emotional effects. 

There is also the matter of binaural effects. According to experts 
it is practically impossible to obtain a binaural effect by the present 
method of sound reproduction, but multiple sound sources appear to 
solve the problem. I understand that the Bell Laboratories have 
made experiments along this line. 

MR. TAYLOR: There are many interesting possibilities in multiple 
sound tracks, but that is apart from the questions brought up for dis- 
cussion. Do you want them on the same film or on separate films? 
These questions are somewhat unrelated. If we can handle film 70 
mm. wide and do not need to use the whole of it for the picture, there 
will be ample space for several sound tracks. One early advantage 
of the separate film was that existing 35 mm. film, utilizing the total 
available space for the picture, could be run as a sound picture, with 
the sound on a separate film, as in the spectacular picture Wings. 
As a matter of economy and convenience it seems highly desirable to 
continue with sound and picture on the same film as long as possible. 

PRESIDENT CRABTREE: There are serious objections to widening 
the film. There are the difficulties of handling a film as wide as 
70 or 80 or 100 mm. ; it takes a Samson to handle it. There is also 
the matter of submitting the film to heat and scratching. We must 
get away from that to get the ultimate in sound reproduction. 

MR. EDWARDS: There is absolutely no handicap with a separate 
sound track from the production standpoint, but there is a serious 
objection to it in the theater today. We must not lose sight of the 
fact that the theaters are already built, and the space in the projection 
department in more than 80 percent of the theaters is very limited. 
The introduction of separate sound tracks, while quite feasible in 
some cases, would not be so in 80 percent of those today. Further- 


more, it must be remembered that where there are two machines to 
be run in synchronism the different starting speeds of two practically 
similar mechanisms have to be considered. 

PRESIDENT CRABTREE: I agree with Mr. Edwards. The thing 
to do is to enlarge the projection room. The exhibitor spends money 
on billboards in front of the theater; Why not spend money to give 
the projectionists more room? The industry from now on must spend 
more money on the equipment required to put the show on the 
screen. We, as a society, should be looking ahead, so that whatever 
we adopt now will anticipate future requirements. That is the pur- 
pose of this discussion. 

It would be an economic waste for the industry to adopt a wide 
film with sound on the same film if within six months it is shown to 
be better to have the sound on separate film. It is only by getting 
everyone's opinion that we can outline the best thing to do. In my 
opinion it is a very important problem, 

MR. EDWARDS: What we must get after is an exchange of ideas 
on the part of the producers. It is well known to every theater man 
that it is easier to get $1000 for stage presentation than $10 for 
the projection room. Until this is changed, we are only shooting in 
the air. 

MR. JAMES: Is it a fact that we are bound to place sound on film 
or wax? Isn't there some other material more permanent? We 
are living in a progressive age and there should be some other 
method of producing sound. 

PRESIDENT CRABTREE: That is a fair question. There has been 
nothing better found to date, or I am sure it would have been adopted. 

MR. STERN: It was my good fortune to canvass the producers and 
discuss the matter of putting sound track on separate film. One 
of the reasons that the industry is being forced to adopt a larger film 
is that by putting the sound track on the same film with the picture 
and cutting the top and bottom of the picture in the camera, the lost 
space represents approximately 20 percent of the original area. 
The result is that everything in the picture is smaller in proportion. 
Furthermore, most of the theaters are employing larger screens than 
they used in the silent picture days, whence the small picture area 
is enlarged so much more on the larger screen that the graininess 
becomes objectionable. If the whole field is utilized for the picture 
alone, putting the sound track on a separate film, there will be no 
necessity for a wide film. 


One thing I failed to mention previously is that, in my plan of pro- 
jecting sound on separate film, the picture runs intermittently, while 
the sound track runs continuously. Replying to Mr. Edwards, in 
the newer theaters two projection heads are usually employed for 
pictures with sound track on separate film one for the picture 
and one for the sound track. The two heads are tied together by a 
shaft so that there is no chance of one starting before the other. 

MR. PHELPS: It seems to me that President Crab tree's mention 
of the binaural effect is worthy of further consideration. I am going 
to ask if the effect could not be achieved by using two sets of loud- 
speakers, at opposite sides of the stage, in conjunction with two sound 
tracks. I think this has dramatic possibilities such as, for example, two 
characters carrying on a conversation from opposite sides of a wide 
screen. I should like to hear something on this point. 

MR. IRBY: In connection with this, several patents have been 
issued recently calling for binaural recording as well as reproduction 
and the tests reported were favorable. 

MR. HILL: Regarding the recording of two sound tracks on 
separate film and then reproducing each sound track separately by 
loudspeakers placed on either side of the stage, this does not work 
out very satisfactorily because of the fact that each ear picks up the 
sound from both loudspeakers. 

The results of several tests, which have been made, show that if a 
head set is used for reception and one sound track output applied to 
each head piece, good binaural effect is produced, due to the fact that 
the sound from one sound track is received by one ear only. If, how- 
ever, loudspeakers are used, the binaural effect is almost entirely lost. 

MR. PALMER: I do not see any particular difficulty with regard to 
space requirements or the synchronizing requirements arising from 
using a separate sound track. The apparatus for the projection 
of sound on the separate track need not be any larger than the present 
film recorder, which takes up very little space. As far as syn- 
chronizing is concerned, there is no difficulty in doing this with the 
projection machine by the present method used in the studio for 
keeping the sound recorders in step with the camera. 

MR. EDWARDS: At the Chinese Theater in Hollywood, when the 
sound recorders were installed the room was packed so that it was 
almost impossible for the men to walk about. The equipment con- 
sisted of standard bases and heads and two magazines; even the lamp 
brackets were left on, and with the amount of space taken up a newly 


designed sound head would be fine. I am not speaking of conditions 
as they should be, but as they are. 

MR. MACNAMARA: By courtesy of the Gaiety Theater last night, 
we witnessed from the projection room the presentation of Hell's 
Angels, and the last speaker's statements were well demonstrated. 
Minimum amount of space has been allowed in the projection room 
to permit the men to go from one machine to the other. The 
extra mechanism the gearing for the disk recording was replaced 
by another for film recording, so that there would be no chance of slip- 
ping out of synchronism. 

MR. BARRELL: Regarding the remarks made by Mr. Stern, 
there is no doubt in my mind that it is preferable to use the old silent 
frame size. A visit to the art museum will indicate that this pro- 
portion is favored by artists. Moreover, by increasing the picture 
size on the screen we increase the apparent graininess of the film. 
A few months ago I read of a German invention of a film in which 
the graininess was so small that enormous magnification could be 
used. There is no question that the picture today is suffering on 
account of the introduction of sound. I wondered what was being 
done to reduce graininess and make it possible to place sound or 
picture in a smaller fiel J than we have' at present. We shall work 
until doomsday striving for proportions better than those of the 
old silent picture. The seventy millimeter width is adaptable only 
for certain types of story; it is suitable only for scenery such 
as Niagara Falls. We must take the tools we have at present, 
and improve them. Reduce the size of the sound track if pos- 
sible, and use the time- tried and thoroughly artistic picture frame 
used for twenty years. We can get into it everything required. 
We are continually reducing the size, letting the graininess ap- 
pear, and ruining the quality of thepicture. 

MR. SHEPPARD: I am only going to refer to the last speaker's 
mention of a process giving extraordinarily high resolution. That 
process is an old one involving the use of silver aluminates. Its 
main difficulty is that the speed is so much less than that of the 
present film, that it would not be of practical use for the present 
purpose. The question of resolving power versus speed is always 
with us. We have to make a compromise. 

MR. HOLMAN: I think these arguments are about the best I 
have ever heard for continuous projection. The practice of putting 
sound and picture on the single strip is a matter of convenience. 

Feb., 1931] 



With continuous projection, there is no such trouble from scratching. 
It is possible, with continuously moving film strips, to drive the film 
with one row of perforations, thus preserving the old silent picture 
area and providing a sound track 50 percent wider than that used 
today. Most of the discussion serves very well to show up the ad- 
vantages of the continuous projector, and a little thought will disclose 
how many of the industry's serious problems will be solved by adopt- 
ing continuous projection. 

MR. RAVEN: In connection with Mr. BarrelTs remarks about the 
destruction of the picture value due to tremendous magnification 
and his reference to the granules of the film showing up, I think one 
of the main faults at the present time, on large as well as small pic- 
tures, is that we have perforated screens. Taking a smooth, opaque 
surface, we puncture it with millions of small perforations, and while 
they cannot be detected at a distance with the naked eye, they are 
there, and we might just as well have so many tiny black spots on the 

MR. NORLING: Graininess seems to be objectionable mostly 
because the grains are in constant motion on the screen. The small 
holes in the sound screen are fixed, and are invisible a short distance 
away from the screen, so that obviously the small holes do not add 
to the graininess of the picture. 

MR. Ross: Mr. Edwards has called attention to the congested 
condition of the projection rooms at the Gaiety and Chinese Theaters, 
where sound was projected on a separate film in the exhibition of 
Hell's Angels. Will Mr. Edwards not be fair enough to admit 
that the sound heads were temporary apparatus made up to meet an 
emergency? We have called attention to the fact that by converting 
the present single-reel upper and lower magazines into two-reel com- 
partment magazines, the present projectors will be no larger than 
those now equipped for sound employing a single film. We believe 
that if projector manufacturers would devote as much attention to 
the redesigning of projectors for separate sound and action film 
as they have to the adoption of single sound films, all the old pro- 
jectors could as easily be converted for separate sound films as for 
single sound films, and at no greater expense or sacrifice of space in 
the projection booth. 

PRESIDENT CRABTREE: It may be a coincidence but the best 
sound quality I have ever heard was in a Broadway theater where 
the sound and picture were placed on separate films. 


An advantage of separate sound and picture films is that each 
can be developed to its correct gamma much more readily. At pres- 
ent a low degree of development of the picture and sound nega- 
tives is in vogue, a practice which is not always conducive to pro- 
duction of the most uniform results. 



Summary. Four adaptations of the comparison microscope are described. One 
is an instrument for comparing two 3 /4 X 1 in. pictures. Another is a sound track 
photometer. The third is an instrument for measuring graininess, and the fourth 
is for checking film dimensions. The principles of application and methods of use are 

Where comparisons are to be made between two objects, the or- 
dinary microscope is at a disadvantage since it is not usually conveni- 
ent to look through it at two things simultaneously. The compari- 
son microscope meets this difficulty. It has two objectives which 
focus on the two objects, and a prism which brings their images 
together so that they can be seen through a single eyepiece. Usually 
these images are separated by a sharp dividing line whose visibility 
indicates the degree of likeness of the objects. If they are exactly 
alike, the dividing line may even disappear, just as it ddes in a photom- 

The Bausch & Lomb Comparison Microscope has been the start- 
ing point in designing four instruments, namely, a picture com- 
parator, a sound track photometer, and instruments for measuring 
the graininess of film, and film dimensions. 

The picture comparator, shown in Fig. 1, is simply a comparison 
microscope arranged for comparing motion picture frames. It can 
be used for making printer light tests, developer tests, or any other 
tests which involve a comparison between two standard size pic- 

To obtain the wide field required for this work objectives, set to 
reduce four times, and a special 20 power eyepiece, are used. " We are 
indebted to Mr. Rayton of the Bausch & Lomb Optical Company 
for the latter. 

* Presented at the Fall 1930 Meeting, New York, N. Y. 

** Redpath Laboratory, DuPont-Pathe Film Mfg. Corp., Parlin, N. J. 




[J. S. M. P. E. 

The films to be compared are placed one under each objective. 
The illumination comes from a 100 watt lamp shining on two diffuse 
reflectors, which can be rotated so as to balance the light. Half of 
one picture and the other half of the second picture are viewed to- 
gether, so that if they match perfectly they appear as one picture. 
Adjustments are provided for moving the halves of the picture into 
alignment, and for bringing the dividing line to any part of the pic- 

FIG. 1. Picture comparator. 

In designing a photometer for measuring sound track densities it 
seemed desirable to have the sound track visible in the instrument so 
that it could be properly centered and the operator could be sure 
that the density of the correct spot was being measured. The 
comparison microscope can be readily converted into a photometer 
meeting this requirement. It is only necessary to focus one objec- 
tive on the sound track and the other on a comparison wedge having 
a known density scale. Since, due to the magnification, the sound 

Feb., 1931] 



track will appear grainy, the comparison wedge should also appear 
grainy. In other words, the wedge should be a strip of film, shading 
from a light to a heavy density. It can be made by mounting the 
film in a stove pipe, and exposing one end to a light. The wedge is 
calibrated on a Martens Photometer, being mounted between strips 
of glass in such a way as not to touch either strip, and framed in 
brass. In this way the difficulties of cemented wedges are avoided. 
After assembling, a density scale is ruled on the frame. 

FIG. 2. Sound track photometer. 

Fig. 2 shows the sound track photometer. Its mechanical features 
are obvious. The disk which is mounted directly below the objec- 
tives contains a set of colored filters which are placed over the wedge 
when measuring the densities of tinted, positive film. 

The setting is made by sliding the wedge until it matches the 
sound track. Densities up to 2.00 can be measured with an accuracy 
of 0.05. This may not be sufficiently accurate for research purposes, 



[J. S. M. P. E. 

but in a practical laboratory the instrument provides decidedly better 
results than are obtained by guess-work. 

Hardy and Jones 1 described an instrument for measuring graini- 
ness which depends on determining the magnification at which the 
graininess just disappears. With this instrument the Kodak Re- 
search Laboratory has investigated the fundamental facts relating 
to graininess and several interesting papers have been published. 

Recently in the Redpath Laboratory an instrument for measuring 
graininess was developed, based on the principle of matching graini- 
ness rather than making it disappear. This instrument evolved 
from the picture comparator. 

FIG. 3. Diagram of graininess comparator. 

In using the picture comparator it was discovered that when two 
densities were made to appear equally bright by adjusting the illu- 
mination, differences in the graininess of the films could be easily 
observed. It occurred to us that by increasing the magnification 
of the fine grained film, and decreasing the magnification of the 
coarser grained film, the apparent graininess could be balanced. The 
relative magnification of the two images would then give a measure 
of the relative graininess. 

Fig. 3 shows how this is done. Light from two lamps, LI and L 2 , 
falls on the opposite sides of the reflector V. The brightness of the 
films can be adjusted to equality either by moving the lamps or by 

Feb., 1931] 



rotating the reflector. The objectives are mounted in sleeves which 
can be raised or lowered by means of two racks with one pinion be- 
tween them. One objective is raised while the other is lowered an 
equal amount. Now, it is obviously possible to mount the objec- 
tives so that each of them gives unit magnification. When so 
mounted, the movement of the sleeves keeps the magnification of one 
objective equal to the reduction of the other, the one optical system 
being always the reverse of the other. It follows that the distance 
between object and image is the same for each side of the instrument, 





Density graininess curves for panchromatic film. 
FIG. 4. 

and therefore both images will come into focus at the same time. 
Usually very little focusing is necessary. For example, in changing 
from equal magnification to a relative magnification of 1.5, the focus- 
ing adjustment must be raised only 2 mm. 

These relationships hold with sufficient accuracy over a relative 
magnification range of 0.7 to 1.5. By providing a series of standards 
of known graininess the range of the instrument can be extended 

The graininess scale is based on a standard strip of film developed 

164 O. E. CONKLIN [J. S. M. P. E. 

to a uniform density. Its graininess is arbitrarily rated 100. In 
making a graininess test, the sample is placed under one objective 
and the standard under the other. The fields are then brought to 
equal illumination, and the relative magnification is adjusted until 
the graininess of the two appears equal. One hundred times the 
relative magnification of the standard then gives the graininess of 
the sample. 

Fig. 4 shows some data on panchromatic film obtained with this 
instrument. Graininess is plotted against density, for a carbonate 
developer and a borax developer ; the curves indicate less graininess 
with the borax developer. Lack of time has limited us to confirming 
some of the published conclusions about graininess, whence we have 
no new data to present on this subject. 

The fourth application of the comparison microscope is the mea- 
surement of film dimensions. In order to maintain accuracy in the 
perforation of film it is necessary to check samples taken at frequent 
intervals. Experience has shown that the ordinary micrometer 
microscope is too slow for this work and will not maintain its ac- 
curacy under' constant usage. Another instrument which may be 
used for film measurements is the comparator. Its accuracy is 
quite constant since there is no micrometer screw to wear out. In 
it the sample is fastened to a sliding holder which carries a finely 
ruled scale. The comparator usually has two microscopes which 
focus, respectively, on the sample and the scale. The distance 
between parts of the sample seen through one microscope can then 
be read on the scale seen through the other. However, the ordinary 
comparator is somewhat slow for routine work, since the eye must 
transfer from one microscope to the other and readings must be 
taken in full. We have, therefore, resorted to the comparison micro- 
scope again and converted it into a special type of comparator, which 
we have named the perforation comparator. It differs in two respects 
from the ordinary kind. First, it is provided with a series of scales 
ruled directly in film dimensions. In this way absolute measure- 
ments are avoided and only the deviations from standard dimensions 
are recorded. Second, the sample and the scale are seen together 
through a single eyepiece, the scale line appearing directly on the 
edges which are being checked. For example, perfect perforation 
is indicated by a scale line appearing on each perforation edge 
as the film is moved along under the microscope. Similarly in 
transverse measurements, scale lines appearing on the edge of the 

Feb., 1931] 



film and on each side of the perforations indicate correct centering 
of the perforations. Where deviations occur, means are provided 
for measuring them. 

Fig. 5 is a diagram of the instrument. It consists essentially of 
a comparison microscope in which a sliding prism (1) has been in- 
troduced so as to shift the image of the perforation edge with respect 
to the scale line. To compensate for chromatic aberration, a fixed 
prism (2) is introduced in the same light 
path, and in the other light path is a plate 
of glass (3) equal to the combined thick- 
ness of the two prisms, thus making the 
light paths equal in length. The eye- 
piece is of the Huyghens type and is 
focused some distance above the com- 
pound prism so that the images of the 
sample and scale overlap. An index mov- 
ing with the sliding prism (1) indicates on 
a scale reading in thousandths of an inch 
the amount of movement necessary to 
bring the perforation edge and scale line 

Fig. 6 shows the perforation compara- 
tor. A separate carriage is provided for 
each type of film. Each carriage is de- 
signed to permit longitudinal and trans- 
verse measurements with a single set- 
ting of the film. The samples slip into a 
slot 0.008 in. wide and are held by pinch- 
ing the slot with a single screw. Two slots 
below, the carriage holds it in position for 
either longitudinal or transverse measure- 
ments and two comparison scales are 
mounted parallel to these slots on the 
top side of the carriage. The scales are 

ruled on highly polished brass by means of a Geneva Society divid- 
ing engine and afterward plated with chromium. They are illumi- 
nated by a beam of red light, and the light transmitted through 
the perforations is green so as to furnish good contrast. 

On looking into the instrument one sees a scale line coinciding 
more or less accurately with the edge of a perforation. The sliding 


FIG. 5. Diagram of perfora- 
tion comparator. 

166 O. E. CONKLIN [J. S. M. P. E. 

prism is then moved until the coincidence is exact and the reading 
of its index is recorded. Then the carriage is moved until the next 
perforation edge and the next scale line appear together under the 
microscope. Usually another setting of the sliding prism is necessary 
to make them coincide. This process is repeated for each perfora- 
tion and the differences between successive settings show how much 
the measured dimensions deviate from standard dimensions. 

Table I is the record of measurements of twenty perforation pitches 
as would be recorded from micrometer microscope readings and 

FIG. 6. Perforation comparator. 

from readings of the perforation comparator. The micrometer 
microscope measurements involve setting five-figure numbers one 
under the other and subtracting each number from the one above it. 
The difference is the pitch which is a four-figure number. The 
perforation comparator measurements involve setting down a series 
of two-figure numbers. Since the numbers are simple and are nearly 
alike decimal points may be omitted. The differences are one-figure 
numbers which indicate to what extent the pitch varies from the 
standard. Only one-third as many figures are read and recorded 
as in the first case. 

Feb., 1931] 




Showing the Figuring Involved in Checking 
Micrometer Microscope 


1 . 1232 


Twenty Perforation Pitches by 
Perforation Comparator 



+ 1 
+ 1 
+ 1 

+ 1 



In practice inspectors check forty perforations per sample for 
regularity, and check the width and centering of the perforations in 
five places. Two inspectors working together with one instrument 
average 220 samples a day. 

The author takes pleasure in acknowledging the counsel and as- 
sistance of Dr. D. R. White in the development of these instruments. 


1 HARDY, A. C., AND JONES, L. A. : "Graininess in Motion Picture Negatives and 
itives," Trans. Soc. Mot. Pict. Eng., No. 14 (May, 1922), p. 107. 


Summary. The Stereoscope is nearly a century old. Stereoscopic photographs 
were made almost simultaneously with the first practical photographic pictures, and 
stereoscopic projection devices for still pictures have been known for over seventy 
years. Motion pictures in relief, when viewed through red and green filters, one for 
each eye, have been shown too often to be now a novelty. 

Fundamentally, stereoscopic vision requires that two eyes, related physiologically 
and psychologically, each view separately distinctly different pictures. Unless the 
taking, printing, projecting, and viewing of pictures are all done in such a way as 
to prevent the left eye from seeing what the right eye sees, there is no license to charac* 
terize the system as stereoscopic. This paper discusses several available methods 
for independent left and right eye vision. 

The aspect or "picture" of a scene or group of articles depends on 
the point of view. Two individuals cannot at the same moment oc- 
cupy precisely the same position ; therefore they see things differently. 
In a smaller degree, but just as truly, distinctly different pictures will 
be viewed by the left and right eyes of each individual observer. 
These two "L" and "R" pictures may have differences which are 
slight, or even insignificant, when viewing flat or distant objects. In 
general, however, nearer objects will hide from view objects which are 
more distant, although what is hidden from the left eye may be seen 
by the right eye, and vice versa. Thus we are able to see completely 
around a small object and partially around a larger obstruction. To 
illustrate simply, hold up a pencil at arm's length. With both 
eyes open, the pencil hides nothing, but if the left eye is closed, the 
pencil covers and hides certain features behind it, while right eye 
closure obliterates other features. 

If a camera is to make a picture record of what is seen, should the 
lens take the position of either eye and perhaps fail to show some- 
thing which is visible to the other eye? Or, should the camera lens 
take a third position which will provide a picture with some other 
part of the background hidden by foreground objects? We are led to 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Research Laboratory, General Electric Co., Schenectacy, N. Y. 


consider two cameras, one to simulate each eye. Or, more conveni- 
ently and practically, we may employ a special camera with two 
lenses making negative pictures, different but coordinated, affording 
positives or prints which we call a stereoscopic pair. If we look at 
the pair of pictures in such manner that the left eye sees only the picture 
taken through the left lens, while the right eye at the same time sees only 
the other picture, the combination of the two views gives the same 
impressions physiological and psychological as were received when 
viewing the original scene. In the composite or stereoscopic impres- 
sion, the foreground is distinctly separated from the background; 
upon closing either eye portions of the background will be lost to 

From extreme youth we have become accustomed to seeing dif- 
ferent overlapping pictures. Instead of being annoyed by double 
images not in exact register, we sense, from the lack of register, solid- 
ity and form, nearness and farness. Continual shifting of alignment 
of the eyes unconsciously brings into register that portion of the two 
views toward which attention is principally directed. 

The question arises as to why each eye cannot select its proper pic- 
ture from a printed pair without having to use viewing machines. 
This can be done over a limited range of picture size and distance, but 
it involves long training in muscular control in order to bring about a 
combination of directing and focusing which is unnatural. The 
mirrors, prisms, or lenses in a well designed and adjusted stereo- 
scopic outfit present the two views to the "L" and "R" eyes 
independently, without eye-strain. 

The stereoscopic effect is real; it is not one of suggestion or 
imagination. If we view in the ordinary manner, a stereoauto- 
chrome, taken in the woods, we see merely a jumble of trees, 
twigs, leaves, and grass. When viewed in the stereoscope the two 
pictures not only clear up into what is large and small, near and far, 
but certain elements (quite indistinguishable from similarly colored 
background in a single view) leap into prominence when each eye, 
independently of the other, views its respective picture. 

Since the usual stereoscope allows but one person at a time to view 
the picture, why could not a pair of pictures be projected onto a screen, 
to be viewed by a group or a large audience? This can be done, and 
has been done on occasion. The fundamental requirement for the 
individual stereoscope must be preserved, viz., the "L" and "R" eye 
of each observer must see the "L" and "R" picture, respectively; 


the "L" eye must be prevented from seeing the "R" picture, and 
the "L" picture must be hidden from the right eye. Several meth- 
ods are recognized for consideration : 

(1) Project the "L" and "R" pair to show side by side, and view 
them by trained muscular accommodation. Even with specially 
acquired ability, the angular limits would greatly restrict the choice 
of position or number of seats in a theater. This arrangement, 
while perhaps the simplest, is considered undesirable for obvious 
reasons, and is adjudged to be without commercial value. 

(2) Project the ' 'L' ' and ' *R" pair to show separately ; provide each 
observer with a viewing device of mirrors, lenses, prisms, etc., to 
direct and restrict each eye to its proper picture. Near and distant 
observers would require a variety of optical equipment. Those 
toward the side of the house, or otherwise situated asymmetrically in 
relation to the "L" and "R" pictures, would require individual 
optical compensating means for one or the other eye. 

(3) Modification of the parallax stereogram of Dr. Ives. In the 
parallax stereogram, the "L" and "R" pair appear to be superposed, 
but are, in reality, intermeshed in a series of alternate lines, and are 
seen through a properly spaced grating which uncovers the lines of the 
"L" picture to the "L" eye. The eyes must be at a predetermined 
distance from the grating and picture. This greatly restricts the 
possible audience. 

(4) Color separation. Project the "L" and "R" pair in different 
overlapping colors onto the screen. Each observer looks through 
spectacles or lorgnettes of colored glass or dyed film, e. g., green before 
the left eye and a complementary red before the right. The comple- 
mentary colors, separately received, give a fairly satisfactory psy- 
chological white and grey monochrome, i. e., the method is not adapted 
for color effects. There may be undesired color effects from unbal- 
anced of irregular vision. A question has been raised concerning the 
possible eye-strain from long continued use of a different color for 
each eye. Because of the cheapness of the viewing screens, this is 
believed to be the only stereoscopic projection system so far shown to 
the largest audiences. It has been regarded as a novelty rather than 
of permanent commercial value. 

(5) Separation by polarization. The "L" and "R" pictures may be 
projected, overlapping each other, by polarized light (through Nicol 
prisms or other devices), the one picture being polarized in a plane 
rotated 90 degrees from the other. Analyzing devices, properly 


adjusted to match the polarizing planes of the projected pictures, 
exclude the "L" picture from the right eye and vice versa. Since the 
polarization is largely broken up after reflection from the usual dif- 
fusing screen, the method requires a metallic screen, or one giving 
specular reflection. This system may be characterized as of scientific 
rather than practical interest. 

(6) Separation by alternate "L" and "R" projection and viewing. 
This idea is quite old. The validity of the method of blinking the 
eyes synchronously with the projected pictures was demonstrated 
by shifting peep holes in extensions on the side of a double projecting 
lantern having a rotating shutter before the lenses. The two views 
appear on the screen to be superposed, but one is cut off before the other 
appears. Persistence of vision was thus relied on to give a continuous 
impression in a projected picture years before the film motion pictures 
were developed. One of the early writers suggested electrical blinkers 
in front of the eyes, worked from contacts on the projector shutter 

Over twenty years ago, the writer constructed and demonstrated 
privately a stereo-projection system in which the 60 cycle house light- 
ing service was used to maintain synchronism between the alternate 
"L" and "R" screen pictures and a portable electric lorgnette. This 
shutter device, on a cord long enough to permit viewing (while ob- 
serving the picture as seen in relief on the screen) was used at vari- 
ous distances and angles. 

Actually, a side view of a screen gives no more distortion for a true 
stereoscopic picture in relief than it does for a single flat picture. 
However, while moving about, some of the effects obtained were quite 

The autochrome process came onto the market at about the time 
of the stereo-projection development cited, and afforded means for 
showing stereo pictures in color by projection on the screen. 

In spite of the realistic and striking effects possible, it has always 
seemed questionable as to how the public would react toward stereo- 
scopic motion pictures requiring a special viewing device for each 
observer. This question can be best answered only by trial, although 
this involves special development all along the line, viz., cameras, 
printers, projectors, and viewers. 

Can a stereoscopic effect be obtained without two pictures and a 
separating device? In the opinion of the writer, the only proper 
answer is, "No." The illusion of reality in a picture may rest upon 


many things, none of which may properly be called stereoscopic. For 
example, perspective, relative size, shadows, color, progressive hazi- 
ness, motion, etc., all aid in estimating distance in a single picture. 
But none of these meet the true stereoscopic test, which is seeing 
with one eye something which is hidden from the other. 


MR. PALMER: I have heard statements made that when viewing stereoscopic 
pictures in which the pictures are separated optically, there are certain people 
who are color blind with respect to viewing the picture in this way. I wonder if 
in Mr. Taylor's investigation of the subject he has found this to be the case. 

Again, is the stereoscopic effect enhanced by viewing the picture from the focal 
point; that is, the point where the negative image was at the time the picture 
was made? 

MR. TAYLOR: I have never found that anyone having two normal eyes would 
have difficulty in seeing the picture in the box form if the lenses were focused. 

As to viewing angle, if we should want to make a stereoscopic picture and see 
it as it appears in nature, the proper relation between the focal length of the taking 
lenses and the distance from which the finished stereogram is viewed, must be 
maintained. I have taken a picture out-of-doors and mounted it; then, looking 
at the view with one eye and at the picture with the other eye, it was possible to 
have the picture register almost exactly with the scene itself. Sometimes it is 
desirable to exaggerate the stereoscopic effect. The eyes of a man are a certain 
distance apart. The eyes of a cow or horse are farther apart. If we should want 
to see as an animal sees, we should have to adjust this distance to suit. This 
procedure is followed by astronomers where they make a separation of 186,000,000 
miles, taking the picture first from one side of the ecliptic, and six months later 
from the other side. On very distant objects the two lenses may be separated 
by a yard or two. This gives a relief effect with mountains which is exagger- 
ated, but which may be desirable in stereoscopic surveys. 

MR. EDWARDS: Don't you think the reason why some people cannot see 
stereoscopically is that they get into the habit of favoring one eye, and they 
really use only one eye. 

Sometimes, with a single, flat picture taken with a single lens we can obtain a 
stereoscopic effect. Why can we not obtain that effect in a motion picture? 
We know that the illusion can be created by having a stationary foreground and 
a moving background. 

MR. TAYLOR: Some people look into a microscope and do not see anything 
because they do not know what points to focus on. That is to some extent a 
matter of training. This can be overcome with a little training. 

As to the statement that single pictures show the stereoscopic effect, I have 
never seen them, although many factors in motion pictures contribute to the 
illusion of reality. Sometimes one may think that nothing is lacking and say 
the effect is stereoscopic, but this seems a misuse of the term. 

MR. MORRALL: Some time ago I took some pictures of a room in which a man 
was working with material which covered him with dust. The lighting was the 
same as they used in a preceding scene, where the dust was not present. When 


projected, I was amazed to see a stereoscopic effect in the picture. This might 
be attributed to the fact that the coating of dust reflected light in such a way that 
it caused the stereoscopic effect. 

MR. Ross: I agree with Mr. Edwards that in motion pictures we frequently 
do find stereoscopic effects. The effect is produced on the West Coast by what 
is known as "back-lighting." Experiments show that back-lighting produces 
this illusion whereas without back-lighting the illusion is not present. 

MR. TAYLOR: I have already stated that many things, such as light and 
shade, relative size, and motion help to estimate distance, but it will be unfor- 
tunate if we confuse the two ideas. 

MR. FRITTS: On viewing a normal scene, the eyes are focused at a definite 
point and the rest of our vision is strained, in the sense that the eye is trying to 
accommodate its vision to all visible planes. It has been suggested that this may 
have something to do with the appreciation of depth. In certain experiments 
which we have made, a picture having a marked foreground and distance was 
viewed through a large uncorrected lens. The eye, under those conditions, is 
subject to eye-strain on the borders, which is akin to the eye-strain of normal 
vision, giving the effect of depth. Is this correct? 

MR. TAYLOR: Without the actual set-up, I can only conjecture. This may be 
a case of factors other than stereoscopic, which aid in judging distance. 

MR. PHELPS: When looking at a contact paper print and then at a lantern 
slide of the same negative, projected on a well-illuminated screen, my eye seems 
to tell me that there is more depth in the projected image than in the paper print. 

MR. TAYLOR: Perhaps because the lantern slide more closely approximates the 
proper light and dark ratios. In real life, we have a large ratio, and in a good 
slide we can more closely approximate this. No print has natural ratios. In 
the case of transparencies we come nearer to the proper values. 



MR. LA PORTE: During the past ten months we have been en- 
gaged in the development of apparatus for taking, processing, and 
exhibiting of pictures. We have used up to this time the 65 mm. 
width, not because that width is the only width, nor that we should 
not consider changing it, but for reasons which are of particular interest. 
We had previously worked with a width of 56 mm. That width was 
chosen on the basis of the present 35 mm. height using standard 
perforations and doubling the width in order to make the width-to- 
height ratio equal to two to one. 

For economic reasons it did not seem that a two to one ratio picture 
having a width of 56 mm. would be a practical proposition in the 
theater, since it would require an additional projector, and very few 
theaters can double the number of projectors and the physical equip- 
ment in the booth. For that reason it seemed that the wide film 
projector would have to be one designed in terms of the 35 mm. ma- 
chine, and would have to be adjustable or in some way interchange- 
able, so that the same projector could be used for both widths. 

On that basis, we increased the height of the 35 mm. frame by one 
perforation, which brought the number of perforations up to five, 
or 25 percent more than before. In order to retain the wide aspect 
of this picture the two to one ratio we had to double the width 
of the frame, and by including the wide sound track and margins we 
finally arrived at the 65 mm. width. 

The standard perforation was retained, as we have encountered 
little trouble from it during the many years we have used the 35 
mm. film, and reports from exchanges, where film that has been out 
through 200 or more projections came back, showed that a very small 
fraction of one percent was damaged beyond further use. 

The increased load due to the wider film is very well taken care 
of by the additional perforation and an additional carrying contact. 
The problem of sound propagation was also considered; the greater 



the number of perforations and teeth, the higher will be the fre- 
quency of any noise induced by the sprocket wheel, and the smaller 
will be the interference per tooth. 

Another thing to be considered was that the recording machines, 
printers, and other apparatus within the studio would be retained, 
and upon retaining a standard perforation, these could be used 
in their present forms without being redesigned or rebuilt. 

FIG. 1. 65 mm. camera mounted on tripod for location 
use, showing motor, housing and finder. 

Apparatus and pictures were made for the 65 mm. width, retaining 
the two to one ratio, with a frame that measured 23 by 46 mm. 
The exhibition of the first test films indicated that in order to obtain 
a picture of sufficient width in many houses, the picture would have 
to be higher than the balcony sight-lines. Also, the fact that in very 
much smaller houses the narrow houses where the width is limited 
to from 20 to 24 feet, a two to one ratio would limit the height 
to about ten or eleven feet and would give the picture somewhat the 


appearance of a strip, the effect increasing as the width of the screen 
is decreased. 

There has been considerable discussion among the directors, particu- 
larly on the West Coast, some of which has appeared in the Proceedings 
of the Academy of Motion Picture Arts and Sciences, relative to 
the size and, more particularly, the shape of the picture. The recom- 
mendations have varied from a width to height ratio of three to five 
to a ratio of two to one. The general consensus of opinion was that 
the best ratio lay between 1.6 to 1 and 1.8 to 1. 

In connection with the pictures to be shown this evening, we have 
adopted what may be termed a compromise, in view of the West 
Coast discussions. The frame is 41 mm. wide and 23 high, giving 
a ratio of 1.78 to 1. 

The cameras used are special cameras designed for this particular 
work. An outstanding feature of these is the adjustable shutter 
opening of 230 degrees maximum. This opening was used, not so 
much for this wide film as for future work on wide film in color, 
which we believe will eventually appear. As we know, in color work 
we must take into account a number of light losses with any process. 

There are two limitations: first, the amount of light that can be 
secured on the set and, second, the relative average aperture of the 
lenses, an increase in aperture meaning a decrease in depth. 

To overcome these difficulties and maintain a speed of 24 frames 
per second it appeared to be necessary to increase the time of exposure 
by increasing the shutter opening. Then, working with wide film, 
and with the shallow field of the wide angle lenses, we are enabled to 
down, and by the reduced aperture obtain increased depth in the 

The idea of a projector capable of accommodating either the wide 
film or the regular 35 mm. film has been retained, and a double 
sprocket with interchangeable aperture has been adopted. The 
sound heads have been provided with similar sprockets and the gates 
have been made adjustable. Two projectors having similar charac- 
teristics will be shown tonight, one using the barrel type of shutter 
and the other one using a very small shutter fitted to work with a lens 
of 1.9 aperture, having a blade smaller than 6 inches. 

In addition to the equipment for processing the wide film, there 
has been installed a reducing optical printer that will reduce 
the 65 mm., or larger, negative to 35 mm. or any intermediate size. 

Feb., 1931] 



FIG. 2. 

Combination projector, right-hand side, housing removed, 
threaded with 65 mm. film. 

A wide film scenic picture was then shown, after which the dis- 
cussion was resumed. 

MR. LA PORTE: The preceding subject was made entirely outdoors 
without limitation as to the amount of light. The next subject is a 
short one representing studio technic. 

In this picture some of the advantages of the wide film are demon- 
strated. More story can be told in a given footage of wide film 
because it is not necessary to take right and left angle shots and a 
straight-through shot followed by a closeup, but rather the entire 
field can be kept in view throughout the entire exposure. 


In taking this picture long shots, medium, and what we might call 
"short shots" were taken, but no closeups at all, in an endeavor to 
keep the images on the screen in about the same proportions that we 
obtain in 35 mm. projection. 

A film illustrating studio technic was shown, after which the 
apparatus shown in the photographs was available for general in- 
spection, and was described by Mr. Del Riccio. 

MR. DEL RICCIO (demonstrating equipment): The steering 
mechanism of the tripod permits it to be driven either along a curved 
or straight line. If driven with the curving clutch thrown in, the 
lens will point in the direction taken by the tripod. If the angular 
clutch is thrown in, the lens will face only in one direction as the tripod 
moves backward, forward, obliquely or sidewise. An attachment 
to the tripod automatically focuses the camera as it moves, regard- 
less of direction. With this focusing arrangement the camera- 
man can watch the action through the film as he takes the picture. 
The director can watch through the finder and manipulate the 
tripods. This results in a saving of time when making ' 'follow shots. ' ' 
The camera can be elevated to a considerable height by means of ex- 

The rear part is in two sections enabling a quick change to be 
made when a magazine is exhausted. The entire mechanism of the 
camera is housed in one small chamber. The shutter is behind the 
disk. The camera can be focused either on the film or on the ground 
glass which drops behind the focusing tube. A series of cams auto- 
matically closes the magazine whenever the ground glass is moved 
behind the lens or a small door in the side of the rear part is opened to 
examine the loops. We have but one set of teeth to move the film. 
The other set is waiting for the decision of the Society of Motion 
Picture Engineers as to how wide the films are going to be. 

The camera is focused, the diaphragm is set, and the lenses are 
locked all from the rear of the camera, where the adjustments are 
accessible to the cameraman while focusing. As the lens is focused 
the finder is automatically focused, and its optical axis is set to con- 
form with that of the objective. 

A new movement has been introduced in this camera a sideward 
motion that is required when operating on floors that are not level. 


The shutter is three-bladed, having a maximum opening of 230 degrees. 
An exposure is obtained which is somewhat greater than the exposure 
used when taking sixteen pictures per second. 

MR. LA PORTE: Three-color pictures, made by the Keller-Dorian 
process, will now be shown. Some of these were made in New York. 
One was taken at Mr. Zukor's home, some were made in Europe, and 
others in Florida. Interspersed among these are various studio films. 


g^3 =4 

FIG. 3. Combination projector. Film gates for 35 mm. and 65 mm. film. 

All excepting the last reel are originals. The latter is composed 
entirely of a series of copies, such as we would have for release. In 
order to demonstrate the difference between the first, second, third, and 
subsequent films, several sequences have been picked out that show 
very definite motion and could not be repeated or re-photographed. 
From six to ten copies have been spliced, one following the other, so 
that the several repeats can be compared with one another. This 
has been done with several sequences. 

CHAIRMAN PALMER: This reel is printed from an original negative. 
All of the color films you have seen up until now have been reversed 

The three-color film was then shown after which the discussion 
was resumed. 


MR. BAUER: What kind of negative was used in making these 
pictures. Was a bi-pack negative used? 

MR. LA PORTE: The Keller-Dorian process was used, with lenticu- 
lated films, very similar to the Eastman Kodacolor process, with 
several minor variations. The lenticulation is horizontal instead of 
vertical. Copies are made by a new optical printing process. There 
is no particular reason why the copies cannot be printed by contact. 

MR. BAUER: There is an apparent lack of registration in some 
of the pictures. How do you account for this ? 

MR. LA PORTE: I believe this is a matter of focus not registration. 
This is a new process; the results are not offered as finished prod- 
ucts. They have been used to establish the correct technic of taking, 
developing, and printing. 

MR. EDWARDS: Is there a limitation in balancing for color? I 
notice that there is a distinct tendency toward the green. 

MR. LA PORTE: There is no reason why we should not be able to 
reproduce any color. The filter has a considerable bearing on this 
matter. The projection filter must be corrected twice: first, for the 
light used in projecting, in order to bring down the blue balance and 
second, to compensate for the slight amber tone or filter effect of 
the film stock itself. Furthermore, the screen we are using is old. 
It has recently been washed but is still rather yellow. 

MR. EDWARDS: With regard to the dimensions of the wide picture, 
it seems to me that the width to height ratio of the wide picture 
would give to many people, especially those in the front of the 
theater, an impression of trying to watch a three-ring circus. The 
eyes may experience some difficulty in covering the whole width of 
the screen. Of course, this would not be true for those sitting at 
the rear of the theater. 

MR. LA PORTE: That is correct; however, the same difficulty is 
found with the speaking stage. It is not any more necessary to view 
the three rings of the circus at once than it is to see the whole width of 
the stage at once. 

MR. Ross: If I understand rightly, the Standards Committee 
of this Society is considering the 50 mm. film as a standard to meet 
all requirements. Mr. La Porte has just referred to the appearance 
of the wide picture in a small theater as a ' 'strip' ' on the screen. This, 
obviously, is the result of projecting a 1 to 1.8 picture onto a screen 
in a square stage opening. I believe it may be necessary to adopt two 
standards of film width, viz., 35 mm. for release prints for small 


theaters and negatives for shooting interiors, especially intermediate 
and closeup shots, and 65 mm. for release prints for de luxe houses 
and for shooting exteriors and long shots. It would be a mistake 
to adopt a single standard of 50 mm. for release prints for both large 
and small theaters, as this would place an undue burden upon the 
smaller houses. It is my further belief that eventually sound will 
be placed on a separate film with two or more sound tracks. In 
producing Hell's Angels it was found necessary to employ a separate 
sound film with two sound tracks in order to properly record the 
sound effects. Furthermore, the industry is learning that the public 
is tiring of dialog pictures and that greater variety both in action 
and sound is required. Musical accompaniment greatly increases 
the emotional influence of dialog pictures ; however, when a musical 
record is superimposed upon a dialog record, the latter is distorted. 
For this reason the musical accompaniment should be placed on a 
separate sound track. The separate sound film with multiple sound 
tracks also allows for the off-stage effects now lacking in the present 
talkies. It would be a simple matter to add sound film magazines on 
either side of the action film magazines, the sound head being placed 
between the sound magazines. By adopting a separate sound film, 
the present 35 mm. release prints can be employed for both small and 
de luxe houses, excepting where wide film is to be shown. This, 
however, does not preclude the use of 65 or 70 mm. negatives for 
recording, to obtain better 35 mm. release prints, especially where 
the projection entails low throws and where graininess must be re- 
duced to a minimum. This condition is generally met in the de luxe 
houses. Furthermore, if the 65 or 70 mm. release prints are to be 
projected in the de luxe houses eventually, these houses, with their 
larger box-office receipts, can more easily afford the installation of 
new 65 or 70 mm. projection equipment. 

MR. LA PORTE: We would not want to exceed the limit of 
magnification of 300 diameters which we now apply to the 35 mm. 
film. It is preferable to keep down to, say, 275. This means that 
a 35 mm. reduction can be magnified to about a 24 foot picture; 
anything beyond that should be obtained from wider film. There 
should always be considered the cases where a larger screen is de- 
sired but where the house is not large enough to accommodate it. 
In order to compromise, we may extend the magnification to 300 
diameters or a little more. A picture smaller than 24 feet in width 
should be projected from a 35 mm. film. This will take care of over 



[j. S. M. P. E. 

60 percent of all theaters. For pictures larger than that the wide 
film should be used. 

MR. Ross: I would like to say that, if the 50 mm. width is adopted 
as standard, this will require the use of three different films. There 

FIG. 4. 

Combination projector, 
hand side. 

View of right- 

will always be the 35 mm. release prints until 35 mm. apparatus 
becomes obsolete. If a 50 mm. width is adopted, we shall also have 
that size film to handle. Recording is now being done on the 35 
mm. film and probably always will be. 

MR. LA PORTE: I do not believe there is any reason for three stand- 

Feb., 1931] 



ards; if we consider 50 mm. film at all, we must look upon it as a 
substitute for the 65 and 70 mm. widths, or that it will eventually dis- 
place 65, 70, and 35 mm. widths, becoming a single universal standard. 
MR. RICHARDSON: Referring to Mr. La Forte's remarks, I believe 

FIG. 5. Printing machine showing working parts. 

it was said that the standard tooth has ample dimensions for the 
heavier film, since the fifth tooth compensates for the added weight. 
I question that statement. After the film has shrunk a trifle, it is 
questionable whether more than one tooth on each side will be pulling 
the film down. The next tooth may be at least half a thousandth of 
an inch out of contact with the film, and the fifth tooth may be any- 


where from two- to three-thousandths of an inch out of contact. 
Here at the studio we are dealing with projectors in perfect condition 
in the hands of experts. In the field the conditions are, in many 
cases, quite the reverse. 

If a film is run in the studio a great many times, without showing 
appreciable wear, it does not follow that it would perform similarly 
on machines in which the intermittent sprocket, the intermittent 
movement, and everything else about the projector is more or less 
worn. When this occurs the projectionist sets the tension down to 
hold the film steady. The result is that the film very quickly becomes 
unfit for use. 

The handling of this heavy film under such conditions demands a 
wider sprocket tooth to provide more wearing surface. This may 
weaken the film, but I do not think that the latter effect is very 

Regarding the picture size, it must be remembered that any addi- 
tion to the height automatically increases the distortion in nine 
theaters out of ten, because these theaters have projection angles 
that are often as great as 27 degrees. If the wide film is made fairly 
high in proportion to its width, the picture will be rather queer look- 
ing, even in the theaters where the projection angle is 23 degrees. 
And, finally, I still believe that if the standard sprocket tooth is 
used we may have good reason for regretting it. 

MR. LA PORTE: You have probably misunderstood me. I said, 
a standard pitch. We use the Bell & Howell standard shape and 
pitch in the negative. In the positive we use the standard pitch. 
An asymmetrical punch is used, of standard size on the sound side 
of the film, and 0.135 in. wide on the other side, carrying a corre- 
sponding tooth. Another set of punches was made with a width 
of 0.130 in. on each side. 

Microscopic examination of brand new film today, regardless of 
width, shows that the film is driven by only one pair of teeth at a 
time, one on each side, and that it must move into position in order 
to bring the next pair into contact with the film. With a film that 
is slightly shrunken, instead of the second pair taking hold next, 
the third pair may take hold, after which the second pair may take 
hold. If the punches are accurate in their spacing, the relaxation 
of the film will change the spacing enough to furnish half-thousandth 
steps. It is the difference and change of tooth pressure point that 
will increase the smoothness with which a sound sprocket can be 

Feb., 1931] 



driven by increasing the number of impulses, thereby raising the 
frequency. There is a slight shift every time a tooth takes hold, 
and even though there may be four or five teeth in contact, only one 
pair of the group is driving. 

The "crossroads" exhibitor will use a 35 mm. version, or reduction, 
of the wide film. He will continue with his present projector. He 
must install a large screen and a more highly corrected objective to 
give him the wide angle without distortion. 

MR. RICHARDSON: When illuminating a wide screen through a 
35 mm. aperture, it is necessary to pass the same amount of light 
through the aperture that would have to be passed through the larger 

FIG. 6. Optical printer set up for reduction of 65 mm. to 35 mm. film. 

aperture. Under this condition, I would say, we would be coming 
back to the same condition that obtained before the shutters were 
changed. We would be likely to warp the film due to heating. 

MR. LA PORTE; That again depends on how much the screen is 
widened. In projecting a 35 mm. film through a 60 degree angle, 
it is not necessary to double the width of the screen, thereby having 
to illuminate double the field, because there is always a limit to the 
size of the screen. In addition to changing the objective, the light 
spot can be made oval instead of circular. 

I am not taking the position that, with 35 mm. equipment for three 
by four film, one can shoot a wide version of 35 mm. without reason- 
able change of equipment and investment; however, the investment 


is small compared with what was required in installing sound equip- 
ment. Furthermore, it is a capital item not an expense item. 

Mr. RICHARDSON: I fear that, due to the excessive magnification 
required, the grain of the film will show up quite badly. 

MR. LA PORTE: At a magnification of 300 diameters we can obtain 
an 18 X 24 foot picture from a 35 mm. normal aperture; if we retain 
the same magnification the graininess will not show up worse in the 
wide picture than it does now. 

MR. RICHARDSON: You are, in effect, putting on a picture 24 
feet wide; about the widest we have attempted is 22 feet wide. 

MR. LA PORTE : We have plenty of pictures 24 feet wide. However, 
we must talk in terms of magnification. If the picture is 20 feet wide 
today, there is no reason why we should add 50 per cent to the width 
in order to include the 60 degree angle that we desire for the wide 
film. We are not seeking a larger picture; we are looking for a 
greater included angle of projection. 

We are seeking improved results in regard to the field which the 
picture covers the ability to tell more story without having to 
continually change from one angle to another. In order to accom- 
plish this we go to the large size film. 

In the matter of reducing the graininess, film manufacturers have 
been continually working on the problem. We have better emulsions 
and greater speed today than we ever had. There is no indication 
now, that, in the course of the next twelve months, we may not see 
higher-speed emulsions, with a very decided reduction in grain. 

MR. STERN: In the demonstration of the wide picture there were 
shown on the screen a semi-long, a short, and long shot, eliminating 
the closeup. It was brought out in the discussion that a similar 
condition existed on the speaking stage. There is quite a difference 
between the technic of the stage and of the screen. In the theater, 
when we desire to view something closely, we use opera glasses. 
These are replaced in motion picture technic by closeups and 
semi-closeups. The long shot in a motion picture story estab- 
lishes the situation; as we tell the details of the story the shots be- 
come closer; in the real serious situations we come to the closeups. 

I have lately observed in the theaters that often, when we see a 
closeup of a person, an individual off stage, who is not shown at all, 
speaks the lines. This illusion carries very well, and therefore if 
we adopt the wider film I believe we shall have to establish an entirely 
new technic for our business. 


MR. LA PORTE: The technic of taking a picture is a matter that 
only directors are qualified to discuss. It was at my request that 
in taking this picture, closeups were avoided and, although a few 
were made, they were afterward cut out. 

The idea I tried to convey was that, by keeping the field entirely 
in view and not having to angle around, footage might be saved, or 
more story covered in the same footage. Whether wide film will 
be used depends on how the public will react to it. 

MR. HIBBERD: Is it your opinion that the 35 mm. film should be 
made on a larger negative and reduced optically for use in small 
theaters with the extended screen, or directly taken on 35 mm. 

MR. LA PORTE: The negative would be a 65 mm. negative. 

MR. HIBBERD: If, instead of increasing the graininess, due to the 
fact that the image is recorded on a larger negative film and reduced, 
do you think that the structure would be improved? 

MR. LA PORTE: If a negative is made on a strip of film 65 mm 
wide and another is made on the same stock 35 mm. wide, the emul- 
sion being the same, the 65 mm. negative will have almost twice as 
many grains as the 35 mm. When the 65 mm. film is reduced the 
grains are reduced in proportion. 

MR. HIBBERD: I was trying to point out the fact that the negative 
grain is the more serious. The positive grain is so fine that what 
is really seen when enlarging beyond a certain point, is the negative 



Summary. Although a simple process of color photography yielding a print which 
faithfully reproduces the colors of nature is greatly needed, most of the research at the 
present time is being directed to the perfection of color motion pictures. Another 
equally important field is the use of color photography in photomechanical printing 
processes, as colored illustrations have come into very extensive use during the past 
fifteen years. The work of different investigators may naturally be divided into (1) 
still photography, including color photographs to be viewed by transmitted light and by 
reflected light, and (2) motion picture color photography. 

Almost from the first years in which motion pictures were used commercially, 
about 1895 to 1900, experimenters have been working on methods of producing them 
in natural colors. The only practical processes enjoying any extensive commercial 
use in the theaters, however, are subtractive processes in which the color is incorporated 
in the film. These subtractive processes, however, are only two-color methods and 
therefore a true spectral record is not realized. 

One additive process has had extensive application for amateur motion pictures for 
over two years. Within the past year a large number of color motion pictures have 
been released with sound accompaniment so that the ultimate is being approached in 
motion picture photography, namely, pictures in color and sound. 

Processes of color photography all date back to the classic experi- 
ment of Clerk Maxwell before the Royal Institution, London, in 
May, 1861. On this occasion Maxwell demonstrated that any shade 
of colored light could be produced by combining various amounts of 
three primary colors, red, green, and blue-violet. He used three 
separate lanterns and placed colored solutions before the lens of each. 
Ferric sulfocyanide was used for the red solution, cupric chloride for 
the green, and an ammoniacal solution of copper sulfate for the blue. 
When the light from all three lanterns was projected on the same 
spot on the screen, a white area appeared; when the red and green 
beams were superimposed, a yellow spot was obtained; with red and 
blue, a magenta spot, and with green and blue, a blue-green spot. 
(See Fig. 1 .) This is called the additive method of color photography. 

* Presented at the Fall 1930 Meeting at New York. (This is a revision of an 
article published in the 1930 American Annual of Photography.) 

** Kodak Research Laboratories, Rochester, N. Y. 



Maxwell also made a photograph of a colored ribbon, which he 
projected with the three lanterns. The difficulty of this work can 
hardly be appreciated unless it is recalled that of necessity he was 
using wet collodion plates. 

Eight years after Maxwell's demonstration a small French booklet 
was published in Paris written by Louis Ducos du Hauron. This 
contained a description of almost all the basic principles of color 
processes which have subsequently been worked out. Credit should 
therefore be given this French inventor for his foresight. In the 
intervening years until his death in 1920, he continued to experiment 
and work out further details of color processes, but was unable to 
realize much commercial success from any one of these methods. 

Of the many references published on color photography, Wall's 




FIG. 1. Diagram of additive color process showing mix- 
ture of three primary colors producing white light. 

History of Three Color Photography, which was published in 1925, is 
perhaps the most valuable, since it represents a compendium of in- 
formation on all phases of the subject. 


It is convenient to divide processes of color photography into two 
classes, the additive and subtractive methods. In the former a colored 
result is produced by starting with a dark screen (one on which no 
light is falling) and adding components of white light until the desired 
color is obtained. An example of this method is Maxwell's experi- 
ment. In the subtractive process it can be considered that a white 
screen is used and that certain parts of white light are subtracted or 
taken away until the desired color is obtained. 

The triangular diagram in Fig. 2 illustrates the principles of the 
subtractive process. As noted in this figure, when a strip of magenta 
gelatin which will absorb green light is placed over a strip of blue- 

190 GLENN E. MATTHEWS [J. S. M. P. E. 

green gelatin which absorbs red light, only blue light is transmitted. 
Thus, a blue image may be obtained either by projecting through a 
blue filter or through a combination of magenta and blue-green filters. 
Similarly, a red image may be obtained by putting a yellow image on 
top of a magenta image, or a green image by putting a blue-green 
image on top of a yellow image. The art of painting makes use of a 
subtractive process since it consists in applying colored pigments to a 
canvas until the resulting combination gives the desired result. It is 
considered that the principles of color in relation to light, absorption 
and reflection of light, the composition of light filters, and the color 
sensitiveness of photographic materials are treated adequately in text- 
books and the reader is referred to such sources if a review of these 
principles is desired. 1 

For purposes of presentation, the subject has been classified as 

I. Still Photography 

A. Transparencies 

1. Additive Processes 
(a) Three-Color 
(6) Two-Color 

2. Subtractive Processes 
(a) Three-Color 

(6) Two-Color 

B. Prints 

1. Additive Processes 

2. Subtractive Processes 
(a) Three-Color 

(6) Two-Color 

II. Motion Picture Photography 

A. Transparencies 

1. Additive Processes 
(a) Three-Color 
(6) Two-Color 

2. Subtractive Processes 
(a) Three-Color 

(V) Two-Color 

B. Prints 

1 Reference sources are as follows: 

A Text-Book of Physics, L. B. Spinney, Macmillan Co., N. Y. 
General Physics, Henry Crew, Macmillan Co., N. Y. 

Colour and Methods of Colour Reproduction, L. C. Martin, Blackie & Sons, 
Ltd., London. 

Light for Students, E. Edser, Macmillan Co., N. Y. 

The Photography of Colored Objects, Eastman Kodak Co., Rochester, N. Y. 



1. Additive Processes 

(a) Three-Color Triple Exposure Methods. One of the earlier 
methods which received some commercial recognition was the three- 
color additive process of Professor Miethe of Berlin. His camera had 
a repeating back, or means of successively exposing the three-color 
separation negatives through the requisite filter placed in front of 
the plates. The positive plates printed from these negatives were 
projected by means of a complicated triple lantern. This process, 
however, and a similar one designed by F. E. Ives, another pioneer in 
color photography, had the objection that the pictures were not taken 
simultaneously and required an intricate lantern for projection. To 
overcome these difficulties, Ives designed a camera wherein two 


FIG. 2. Diagram of subtractive color process. Three- 
color filters, magenta (or minus green), blue-green (or 
minus red), and yellow (or minus blue), respectively, cut 
in shape of segment (left) are superposed to form a tri- 
angle (right). Where the different pah's overlap at the 
corners, the primary colors, red, green, and blue- violet, are 
produced. Where all three filters overlap in the center 
triangle, no light is transmitted because each filter absorbs 
one of the primary colors. 

special mirrors split up the light entering the single lens and exposed 
the three plates simultaneously. By a similar principle the three- 
color impressions could be examined in a special viewing outfit. Ives 
also designed a method for making stereoscopic pairs of three-color 
positives (Kromograms) which were viewed in a device called the 
"Kromskop." Cameras for making three-color negatives have also 
been designed by Butler, Sanger-Shepherd, Rene*-Gilbert, and others. 
Screen Plate Processes. One of the novel processes suggested by 
Du Hauron was that the surface of a plate might be covered with tiny 
filters, red, green, and blue, and then the sensitive emulsion coated on 



[J. S. M. p. E. 

top. By photographing through the back of the plate an image would 
be obtained which would be cut up into tiny sections similar in size and 
shape to the filter sections. Several systems of making these ' 'screen' ' 
plates have been worked out. The methods may be divided into two 
groups according as they yield (a) a regular pattern, or (b) an ir- 
regular pattern. Examples of the former would be methods of ruling 
a series of red, green, and blue lines on the plate surface or producing 
a mosaic of tiny red, blue, and green squares. The latter or irregular 
method is represented by processes in which colored particles one 
layer thick are dusted on the plate surface. 

In 1892 the first recorded attempt to make a screen plate of the 

FIG. 3. Reproduction of a McDonough screen plate pic- 
ture showing line image. R red; G green; B blue. 

regular type was made by J. Joly of Dublin. He obtained rather 
pleasing results by ruled-line methods. His line screen was on a 
separate plate and after the negative had been exposed, a positive was 
printed and placed carefully in register behind another line screen. 
About the same time, J. W. McDonough of Chicago, 111., introduced 
a process somewhat similar to Joly's method. Fig. 3 is a repro- 
duction of a slide made by the McDonough process. 

The most successful commercial process, however, is the Auto- 
chrome, which was introduced by A. & L. Lumiere in France, in 1907. 
This is an irregular screen process wherein minute grains of potato 
starch, varying in form and 'size, are dyed in separate batches, blue, 
green, and red, with dyes especially selected for the purpose. The 

Feb., 1931] 



dyed grains are mixed in the ratio of four green to three red to two 
blue, and are dusted on the surface of the plate. The interstices are 
filled with a black powder and the layer rolled in under pressure. 
The plate is then varnished and coated with a panchromatic emulsion. 
When finished, there are over four million of these color filters per 
square inch. (See Fig. 4.) Although the three colors should combine 
to give the effect of white when looking through the screen, they 

FIG. 4. Photomicrograph of Lumiere autochrome 
starch grain screen plate. (Reproduced from "Photog- 
raphy in Colors," G. L. Johnson, Button and Co., New 
York, 1922.) 

actually appear a salmon pink. Exposure is made through the glass 
slide so the light will have to pass through the colored screen before 
reaching the emulsion. After the exposure, the plate is developed 
and then bleached in acid permanganate, which dissolves the silver 
negative image but does not attack the unexposed emulsion. An 
exposure to white light now makes the remaining area developable, 
and after the second development a positive image is obtained. 
The process of bleaching, exposing, and redeveloping is known as a 

194 GLENN E. MATTHEWS [J. S. M. P. E. 

reversal process, because the original negative is converted into a 

The Agfa color screen plate was originally announced in 1916 but 
was not introduced until 1923. This plate has a three-color screen 
similar to that of the Autochrome except that dyed particles of gum 
arabic rolled out in collodion are used. Color screen methods were 
first applied with some commercial success to roll film and film packs 
by the Lignose Company of Berlin, in 1927. 

The Paget screen plate introduced about 1912 was very popular 
for several years. The color screen and the sensitive emulsion were 
on separate plates, thus eliminating some of the difficulties of screen 
plate manufacture. In the event that the picture was spoiled, the 
screen could be used again. When binding up the transparency it 
was somewhat difficult to register the color screen. Although with- 
drawn from the market for a few years, the plate was introduced again 
during 1927 under the name "Duplex Color Plates." 

The Finlay color process, introduced during 1930, uses a separate 
taking screen and a specially sensitive panchromatic emulsion. It 
is claimed that exposures may be made in one-fifth to one-fiftieth 
of a second at //4.5 for street scenes in good sunlight, and one- 
hundredth of a second for seascapes. Contact positives are printed 
from the negative and bound into register for inspection. The 
first aerial color photographs were made by this process by a staff 
photographer of the National Geographic Society during the sum- 
mer of 1930. The pictures were exposed from army dirigibles, the 
engines being turned off to reduce vibration during the exposure. 

Numerous other screen processes have been worked out but very 
few of them compare with the Autochrome in quality and fineness of 
the screen particles, the uniformity of the product, and the beauty of 
the color rendering. Even the Autochrome process has certain limi- 
tations, however, for it is necessary to use a very thin emulsion coat- 
ing, and such a coating has a narrow range of gradation or ability to 
reproduce a scale of tones. The plates are also very dense and re- 
quire stronger illumination than ordinary plates for projection. 

Bi-Pack and Tri-Pack Methods. Several methods of exposing two 
or three films simultaneously have been suggested. The films (or 
plates) are arranged as a pack so that the two upper films (or inter- 
posed filters) transmit certain portions of the light in exposing the 
different layers, and a set of three-color separation negatives is ob- 
tained. The order of exposure varies with different processes but 


the usual procedure is to place the blue-sensitive film uppermost, 
then the green, and then the red. It is impossible to obtain critical 
sharpness by such a method although some rather pleasing results 
have been produced. 

(b) Two-Color Additive. The majority of transparency processes 
are three-color processes but a few two-color additive methods have 
been worked out. A two-color line screen process has also been 

2. Color Reproduction by Subtractive Processes 

Thus far methods have been discussed in which the final picture 
is made by superimposing, or adding, lights of two or three primary 
colors. In nature, however, substances are not colored in this way 
but, instead, they absorb or subtract certain component parts of the 
visible spectrum of white light and reflect the remainder. It is this 
composite reflected portion which is the color the normal eye records 
as the natural color of the object. 

(a) Three-Color Methods. When preparing a three-color trans- 
parency by the subtractive process, it is necessary to make three 
positive color records either on thin gelatin coated films or tissues, and 
superimpose these in register. Methods of securing these positive 
color records may be classified, as follows: (i) dye mordanting and 
toning methods, (ii) carbon (or pigment) transfer, (Hi) imbibition, 
(iv) hard and soft gelatin methods, and (v) relief processes. 

(i) Dye Mordanting and Toning Processes. In these processes, 
positives are printed from a set of three-color separation negatives 
and the silver image on each positive is changed to a compound salt 
which will mordant or absorb basic dyes. The final dye images are 
distributed throughout the original gelatin film so that the entire film 
must be transferred to the final support. 

It is quite difficult to secure true complementary colors by chemi- 
cal toning methods, but nevertheless, some very pleasing results 
have been produced. Iron toning is occasionally used to produce a 
blue image, and mercury (iodide) gives a yellow image ; there is no 
satisfactory toning method known for making a red image, although 
the reddish-brown image obtained with uranium toning has found 
some adaptation. Toning methods are sometimes used in conjunc- 
tion with other color processes. 

(ii) Carbon or Pigment Transfer. This process makes use of a 
property that bichromated gelatin possesses, of becoming tanned or 

196 GLENN E. MATTHEWS [J. S. M. P. E. 

hardened when exposed to light. If a plate is coated with bichro- 
mated gelatin and is placed behind a negative, as in Fig. 5, and then 
exposed to light, only those parts of the bichromated plate which the 
light does not reach will remain unhardened and therefore soluble in 
hot water, while the parts exposed to the light will be insoluble in hot 

Exposure is usually made through the back of the film or plate in 
order that the delicate highlights may not be washed off during the 
hot water development. After the soluble parts have been removed 
the image remaining may be dyed up by choosing dyes which are 
absorbed by tanned gelatin. The dyes must be complementary 2 
to the filters through which the negative was exposed; thus the green 
filter picture is dyed magenta, the blue filter picture is dyed yellow, 

Tanrxed qnd Insoluble irt 
Hot Water ^ 

PWe. coated with _J Ckr- WbiU Light 


Soluble in Hot Water 
Not Tanned 

FIG. 5. Effect of light on a bichromated gelatin plate. 

and the red filter picture is dyed blue-green. When the three posi- 
tives thus obtained are cemented together in register, a transparent 
color reproduction of the original subject will be obtained. 

(Hi) Imbibition Processes. Transparencies by the imbibition proc- 
ess consist of dye images in a single gelatin layer. When a dyed relief 
image in gelatin is brought into intimate contact with a plain gelatin 
surface, the dye tends to wander to the other surface, or become im- 
bibed by the gelatin. Such imbibed images are inclined to be fuzzy 
and expedients are therefore taken to prevent spreading of the dye. 
Registration of such images is also very difficult but very pleasing 
results have been obtained. 

(iv) Hard and Soft Gelatin Process. A method was introduced in 
Germany in 1906 known as the pinatype process, which utilized the 
fact that certain dyes will stain soft gelatin in preference to hard gela- 

2 Complementary dyes are those which absorb the light which the filter 
dyes transmit. 


tin. The process as originally introduced was tedious as it required 
nine separate printings. Three transparencies are prepared from the 
original three-color separation negatives and three print plates on 
bichromated gelatin from the transparencies. The print plates are 
then dyed up with dyes which are only absorbed by soft gelatin and a 
positive image is produced on the print plate which contains an in- 
visible negative image of tanned gelatin. The dye image may subse- 
quently be transferred to another surface if desired. 

(v) Relief Processes. There are three methods commonly em- 
ployed for producing a relief image in gelatin, (a) the use of the 
tanning action of a bichromate solution on the gelatin around the 
particles of silver comprising an image. The gelatin relief can then 
be stained up and used as a matrix, (b) The use of an oxidizing 
solution such as hydrogen peroxide, which dissolves away the image 
and attacks the gelatin immediately around each silver particle com- 
prising the image. The gelatin film is then washed, fixed, and dyed. 
(c) The use of the tanning action of an oxidized developer on gelatin 
to form a relief image which is subsequently dyed up. In (a) and (c) 
the silver image is removed by treatment with a reducer before dyeing. 
In addition to the above methods of securing a relief, the tanning 
action of light on bichromated gelatin may also be used, as described 
under carbon or pigment transfer methods. 

(b) Two-Color Methods. Because of the complication of a three- 
color process, several investigators have tried to perfect a two-color 
subtractive process. The possibility of getting satisfactory results 
with the subtractive method is somewhat greater than with the addi- 
tive method. With the latter, two colors must exactly balance each 
other, or be complementary to one another, in order to obtain true 
whites and blacks. In the former or subtractive method, whites are 
obtained by the absence of color and blacks by using both colors in 
full strength, so that colors may be used which are not exactly com- 
plementary and the range of usable colors is greatly extended. 

The method of preparing transparencies or lantern slides by this 
process is essentially the same as for a three-color subtractive process. 
The final result consists of two plates, films or tissues, which have been 
dyed by some suitable method and then superimposed in register. 

The Kodachrome process of color portraiture, worked out by J. G. 
Capstaff and introduced in 1915, made use of the property possessed 
by certain dyes of staining soft in preference to hard gelatin. Two 
plates were exposed behind their respective filters, developed, and 

198 GLENN E. MATTHEWS [J. S. M. P. E. 

then converted without fixing into dyed positives. This process 
used a tanning bleacher which removed the original negative image 
and simultaneously hardened the gelatin in proportion to the amount 
of silver image present. 

For portraiture, a two-color subtractive process is admirably 
adapted. It is also useful for photographing certain flowers, still life, 
or fashion scenes in which reds, greens, or orange predominate. It is 
unsuitable, however, for landscape work where there is an excess of 
blue, blue-green, and violet. For clinical photography and photo- 
micrography it finds useful application. 


Although most of the color transparency processes are capable 
under certain conditions of yielding color prints, the majority of the 
print processes of commercial interest have been worked out primarily 
as print processes. The average individual prefers a photograph 
that can be examined in the hand or hung upon the wall to one which 
must be held before an illuminator or projected upon a screen. 

1. Additive Print Processes 

Numerous attempts have been made to perfect an additive color 
print process but none have met with any practical success. Sub- 
tractive processes are much simpler to work and the majority of print 
processes therefore have been subtractive methods. 

2. Subtractive Processes 

All of the methods described previously under subtractive trans- 
parency processes are adaptable to making prints. The final stage 
of the process usually consists in superimposing two- or three-color 
tissues or gelatin films in register or transferring the image by im- 
bibition to a paper support. 

(a) Three- Color Methods 

(i) Dye Toning Processes. More or less degradation results by this 
method as the colors often wander and the print is usually rather dark, 
because the light has to penetrate several layers of film and be re- 
flected back through them. Ives' Hichrome process is one of the best 
examples of this method. 

(ii) Transfer Processes. Under the general term transfer proc- 
esses, may be grouped those methods of producing color prints wherein 
bichromated tissues containing the respective color records are 


transferred from their original support to a paper support. Three- 
color carbon prints are prepared by applying a mixture of gelatin and 
pigment to a thin piece of film support, sensitizing the gelatin in bi- 
chromate solution, exposing under the respective color negative 
through the film side of the tissue, dissolving off the soluble gelatin in 
hot water, and mounting, gelatin side down, on a piece of smooth white 
paper. After the sheets have remained in contact a short time, the 
film support is stripped off, the operation usually being carried out 
under water. The yellow tissue is ordinarily mounted first, then the 
blue-green, and then the magenta. Some of the finest examples of 
this process produced in America are those of J. W. Allison of New 
York and Jeffery White of Detroit, Mich. 

In the original Raylo process introduced in 1923, three exposures 
were made successively and automatically on one plate, through the 
three primary filters, yielding a negative. The method of printing 
gave any number of 5 in. by 7 in. pictures on paper and is a novel 
application of the carbon process. A sheet of film base coated with 
three patches of pigmented gelatin was stretched in a frame, exposed 
to the enlarged images of the negative, and then developed in the 
usual way in hot water. By means of a special registering device, 
the final superimposition of the three tissues was claimed to be 
accomplished with ease. More recently, the inventor of the Raylo 
process, Mr. H. C. J. Deeks, supplied prepared pigmented aceto- 
cellulose sheets for printing from any set of three-color negatives. 
Each sheet is coated with a light sensitive silver halide emulsion con- 
taining the pigment. After exposure and development in a tanning 
developer, the relief image is washed with hot water and the silver 
image is removed by bleaching and fixing. The prints on these 
pigmented tissues are then transferred to a paper support. 

In the Ozobrome methods, bromide prints made from the original 
three-color negatives are brought in contact with the respective color 
tissues soaked a short time previously in a bichromate-ferricyanide- 
bromide bath, and the bromide print stripped off the tissue, which 
now bears the image of the print. The tissues are then developed, 
fastened to a temporary support, brought into register, and finally 
transferred to a permanent paper support. 

(ii) Imbibition Processes. Color prints by the imbibition process 
are made by starting with a blank sheet of gelatin coated paper and 
causing the coating to take up successively or "imbibe" dyes from 
color images from the ."print plate" covered with unhardened gelatin 

200 GLENN E. MATTHEWS [J. S. M. P. E. 

Any number of prints may be made from one group of print plates. 
The dyes used in this process will only stain soft gelatin. In another 
imbibition process, the Sanger-Shepherd, the reverse is true since it 
depends on dyes which will stain hardened gelatin. Very pleasing 
results may be obtained with both two- and three-color imbibition 

(w) Relief Processes. A novel wash-off relief process using im- 
bibition to prepare the final print was introduced in Germany in 1925 
under the name "Jos-Pe." Printing plates were prepared from a set 
of three-color negatives by projection onto glass plates coated with a 
gelatino-bromide emulsion. The plates are exposed through the 
back and developed in a developer which differentially hardens the 
gelatin according to the amount of silver image formed. A relief 
image is obtained by washing the fixed-out plates in hot water. 
Prints are made from these dyed-up printing plates by imbibition, 
registration being simplified since the printing plates are quite trans- 

(v) Bleach-Out Methods. An ingenious method for changing a 
color transparency into a color print, which unfortunately, has thus 
far had very little commercial success, is the bleach-out process first 
worked out by J. H. Smith in 1895 and known as "Utocolor." This 
process had been suggested in 1867 by Du Hauron and Charles Cros 
from purely theoretical reasoning. It depends on the property 
certain dyes possess of bleaching out when exposed to specific wave- 
lengths of light. Paper is coated with an intimate mixture of three 
such dyes, red, yellow, and blue. The color transparency is placed 
in contact with the paper and by virtue of the bleaching properties of 
the dyes, the paper is changed into a color print. Uneven bleaching, 
distortion from heat, and fugitiveness of the dyes are some of the 
difficulties encountered. Although these limitations are serious, this 
method offers great possibilities if it is ultimately worked out satis- 

(vi) Three- and Four -Color Photomechanical Reproduction. The 
most outstanding use of color photography for many years has been 
the making of three-color reproductions in books and magazines by 
photo-mechanical methods. Two methods are used, depending upon 
the accessibility of the subject, (4) the Indirect and (B) the Direct 

In the former, three-color separation negatives are prepared, trans- 
parencies are made from these negatives, and screen negatives on wet 


collodion plates are finally obtained from the transparency by inter- 
posing in the camera in front of the sensitive photographic plate, 
a glass plate evenly ruled with a fine cross line screen (about 150 lines 
to the inch). 

The direct method avoids the making of the first negative and the 
transparency, since the three screen negatives are made by direct 
photography of the colored subject. For each separate screen nega- 
tive, the red, blue, and green, the screen is rotated, making each pat- 
tern at an angle of 22 Y 2 degrees to 30 degrees from the others. When 
the lines of the screen cross at smaller angles, a disagreeable pattern 
or moire is produced in the final printing. Engraved copper color 
plates are prepared from each color separation negative and printed 
by inking up with suitable greasy ink pigments. 

(b) Two-Color Subtr active Processes. Several two-color processes 
for preparing color prints have been worked out, using most of the 
methods described under three-color processes. Very pleasing results 
have been produced with two-color imbibition and by carbon transfer 


Processes of still photography always lack one important character- 
istic motion, for life as the eyes see it, is associated closely with 
movement. This fact led several investigators about 1890 to attempt 
to reproduce motion by means of photography. As we know today, 
a standard motion picture film consists of a series of slightly differing 
pictures printed on a narrow film strip, 16 pictures to each foot of film. 
When intermittently projected at a rate of one foot or more per 
second, the eyes, by persistence of vision, see these images gradually 
dissolving one into another, because the impression of one picture 
does not quite disappear before the succeeding one overlaps it. 


1 . A dditive Motion Picture Processes 

(a) Three-Color Methods. Soon after motion pictures were intro- 
duced attempts were made to perfect a color process of cinematog- 
raphy. One of the earliest tri-color additive methods was worked out 
in England by W. Friese-Greene. It consisted in taking the pictures 
successively on a single film strip through primary filters incorporated 
in a rotating sector wheel, and reconstructing them by projection in a 



[J. S. M. P. E. 

similar manner through color filters. It was found, however, that a 
projection speed of 70 pictures per second was necessary, which proved 
entirely impracticable because of the excessive wear on the machine 
and the film. To reduce this abnormal speed the pictures were taken 
at normal speed simultaneously through three lenses on three separate 
films and projected in much the same way. This method had its 
drawbacks also, since three times as much film was required and 
optical errors were introduced, which made it impossible to exactly 
superimpose pictures taken from different points of view and at 

FIG. 6. Comparison of Gaumont three-color negative (right) and standard 
35 mm. negative films. 

different times. These are known as parallax and fringing errors, 

Gaumont tried to overcome the need of using extra film by making 
the three records simultaneously on one film and reducing the size 
of the records so that they occupied 2.25 times instead of 3 times the 
space of a standard picture. (See Fig. 6.) Both the camera and the 
projector were equipped with a special three-lens projection system 
and the three primary filters were placed in front of the lens on the 

Feb., 1931] 



camera and the projector. The results given by this process were 
very pleasing, but it had the objection that special equipment was 
required for showing the pictures and it used more film than standard 
motion picture photography. 

In almost all of the three-color additive processes, the film is moved 
intermittently, but J. Szczepanik designed a complicated camera and 
projector, about 1925, in each of which the film is moved continuously. 
Intermittent motion is dispensed with in the camera by having an 
endless chain of 18 lenses moving synchronously with the film behind 
a collimating lens, three pictures being exposed at any time through 
primary filters. The projector is even more complicated, and refer- 
ence should be made to the literature for details of its construction. 

Other three-color additive processes which were being exploited 
during 1929-30 were the Wolff -Heide and the Herault processes. 

FIG. 7. Photomicrograph of cross section of Kodacolor 
film (thick black line is the emulsion). 

Natural color motion pictures for the amateur became available in 
1'928 when Kodacolor film was announced for use in 16 mm. equip- 
ment distributed by the Eastman Kodak Company. The method is 
a commercial expansion of a process worked out in principle by R. 
Berthon and A. Keller-Dorian of France, between 1908 and 1925. 
In this latter year, rights were purchased by the Kodak Company for 
development, particularly as an amateur process of color cinematog- 

Kodacolor is a three-color additive process which realizes the 
principles of a line screen method without the added difficulty of 
ruling a screen on the film support. The process is based on a 
means of impressing a series of microscopic cylindrical lenses into 
and across the support side of panchromatic film. (See Fig. 7.) 
A banded three-color filter is fitted into a holder in front of the 
lens of the camera and projector. The film is threaded in the 



[J. S. M. P. E. 

camera with the emulsion side away from the lens so that the light, 
before it reaches the sensitive emulsion, must be transmitted by the 
tiny embossed lenses, each one of which thus images the bands of the 
color filter on the film. If the subject is white, all three color filters 
allow light to pass and three lines are exposed under each lens element. 
If the subject is red, that is, if it reflects red light, only the red parts 
of the filter transmit the light, and the emulsion areas illuminated by 
this section of the filter will be exposed. With colors that are made 
up of more than one primary color it follows that more than one part 
of the tri-color filter will transmit the light. 

Perhaps this may be made a little clearer if only one lens element 
and one color of light, say, blue, is considered as shown in Fig. 8. 




FIG. 8. 

Action of blue light on single lens element of 
Kodacolor film. 

Here it is seen that the blue light exposes an area about one-third 
that under the lens element (No. 1). On development this area 
becomes opaque (No. 2). The film is then bleached, and the remain- 
ing silver salts are given a controlled exposure (No. 3) and developed 
up. Now the area affected by the blue light becomes clear and 
transparent, while the areas corresponding with the red and green 
filter segments are opaque (No. 4) . When white light is directed on 
this single lens section, it passes through the area where the blue 
light exposed the film, and since the optical system is reversible, it 
follows that the light will strike the blue segment of the filter and form 
a blue spot on the screen, since no light reaches either the green or red 
filter segments. 

Feb., 1931] 



In other words, all the tiny line areas transmit all, part, or no light, 
according as the subject reflects all, part, or none, of the correspond- 
ing colored light. The various colors are recombined on the screen 
to reproduce the natural colors of the subject photographed. 

Examination of an actual picture will make this principle clearer. 
Fig. 9 shows, on the left, a picture on Kodacolor film (actual size) of a 
child wearing a red hat. The child's head stands out in silhouette 
against a blue sky. In the enlargement on the right, of one picture of 
the series, the characteristic line composition of a Kodacolor picture 
is readily discernible. 3 Note that the lines are alternately dark and 

FIG. 9. Picture on Kodacolor film of child with red hat against a blue 
sky ; and enlargement showing line composition. Note displacement of lines 
in hat area (.4) compared with sky area (B). 

light where the red hat is reproduced (shown by arrow ^4), thus allow- 
ing light to pass through the image so that it will be transmitted only 
by the red part of the color filter. In the area representing the blue 
sky, the lines are dark and light, but they are displaced slightly from 
their position in the area of the red hat. This is best seen in the 
parts of the sky next to the hat (shown by arrow B). The sky area 
reproduces as blue on the screen, since only the blue part of the filter 
will receive and transmit the light passing through that part of the 

3 When Kodacolor pictures are projected on the screen, the lines, of course 
are invisible at the normal viewing distance. 

206 GLENN E. MATTHEWS [J. S. M. P. E. 

Motion portraits made by the Kodacolor process using artificial 
light in a specially constructed studio were shown at Buffalo, N. Y., in 
May, 1929. 

(b) Two-Color Additive Processes. Difficulties attending three- 
color processes prompted W. Friese-Greene and others to try to 
devise satisfactory two-color additive processes. One of these 
known as "Kinemacolor" enjoyed some commercial success. Like 
Friese-Greene's first method, it used a rotating disk or shutter of 
color filters before the lens. The pictures were taken alternately 
through red and green filters at twice the normal speed and projected 
at the same speed. Considerable trouble from color fringing was 
found with these methods. About 1925 C. Friese-Greene, the son of 
the previous inventor, produced a process called "Spectrum Films" 
which employs a special color shutter in the taking camera that is 
claimed to reduce some of the trouble from these optical errors. 

The Busch two-color additive process utilizes a twin lens camera 
for photographing the pictures, one above the other, on each single 
frame of the negative film, which runs horizontally through the 
camera. Contact prints are so projected that the image pairs are 
superimposed on the screen. This process has been recommended 
especially for photographing surgical cases. 

Another method of securing two-color additive effects consisted in 
dyeing up the alternate frames of a Kinemacolor or allied positive, 
red and green, respectively, and projecting the film at twice the 
normal speed. This gave an effect similar to that of using a rotating 
color sector wheel before the projector lens. 

An additional two-color additive process which was being ex- 
ploited during 1929-30 was the Ray col process. 

An amateur color process known as Vitacoloralso appeared recently, 
incorporating the old Kinemacolor principle (see below) , except that a 
multicolor sector wheel is rotated in front of the camera and projector 
lenses are used instead of a shutter with only three primary colors. 
Alternate frames are exposed through this color sector at 26 to 28 
pictures per second. 

2. Subtractive Motion Picture Color Processes 

(a) Three-Color Methods. Three-color sub tractive processes pre- 
sent very great difficulties, as it would be necessary, by dyed bi- 
chromate or dye mordanting methods, to apply three successive color 
layers and recoat with gelatin after each application. Subtractive 


processes using three colors were introduced during 1928-29, called 
the Zoechrome and Splendicolor methods. Most of the commercially 
workable processes, however, are two-color subtractive methods. 

(b) Two-Color Methods. In these, color may be incorporated in one 
emulsion layer on opposite sides of the film or in two layers on one 
side of the film. Several methods have been worked out ; some use a 
dye mordant treatment, some an imbibition process, and others 
chemical toning methods. Three methods of taking pictures have 
been adopted: simple alternate exposure through red and green 
filters; the use of twin lenses corrected to the wave-lengths of the 
respective filters; the use of optical systems of semi-transparent 
mirrors which split the beam of light and expose the two images 
simultaneously. The last method overcomes all parallax and fringing 

P. D. Brewster adapted the bi-pack scheme to cinematography. 
He used a double coated negative film containing a transparent 
emulsion sensitive to the blue-green on the side of the film toward the 
lens, and on the other side, either a panchromatic emulsion or one 
sensitive to the red, orange, and yellow. After processing the nega- 
tive film in the usual way, the images were bleached and dyed with 
basic dyes of the same color as used for the filters. The color nega- 
tive obtained was used to make prints on double coated positive film. 
A prism beam-splitter was used in the printer and the two images 
printed through the respective filters onto opposite sides of the film. 
The final silver images were bleached and dyed in the same colors as 
the printing filters. The color positive could be projected in the 
usual way on a standard projector. 

Several methods of producing two images on single coated film have 
been worked out by Ives, Kelley, Fox, and others. A typical ex- 
ample is one in which the first image produced is toned blue with an 
iron toner and, before fixing, a second image is printed in the remaining 
silver halide. During development, the alkali present in the de- 
veloper converts the blue image to a colorless salt. The second 
image is then treated with a vanadium mordant bleach and dye toned. 
When the film is passed through an acid solution, the original blue 
image is restored. 

Numerous processes have been patented on the use of double 
coated stock for printing the positive record. 

A typical two-color subtractive process is "Kodachrome" worked 
out by J. G. Capstaff of the Kodak Research Laboratories. By 

208 GLENN E. MATTHEWS [J. S. M. P. E. 

means of a beam-splitter optical system, complementary images are 
exposed simultaneously on panchromatic negative film. A master 
positive print is made by contact from the original negative. By 
using a special projection printer, a duplicate negative print is made 
from the master positive. In the print the complementary images 
are in exact register on opposite sides of a double coated film. This 
duplicate negative is bleached until the images have disappeared, 
the bleach bath hardening the film only in the parts where the 
image previously existed. The two sides of the film are then dyed 
in colors complementary to the filters through which the original 
negative was exposed, the dye entering the film only in the un- 
hardened areas, thus producing positive dye images. The color 
film may be projected the same as standard black and white motion 

Another two-color subtractive process is the "Technicolor" founded 
on the Comstock patents. This was worked out originally as a relief 
process, but about 1928 was changed to an imbibition process. The 
negative or master film is photographed as before, two pictures at a 
time, one "frame" or picture carrying the component of one set of 
colors, the next its complement or if desired three-color components 
are used. The developed negative is printed by a mechanism which 
jumps the negative so that the red separation images appear in a 
continuous film, the blue images in another continuous film in 
other words, the positive film is moved forward one frame at a time 
and the negative two frames at a time. These two films are developed 
to produce a relief image, and are then run along a steel plate succes- 
sively under great pressure, in contact with the film to be used for 
projection, the dyed images being "printed" much as the red, blue, 
and yellow plates are printed in making color reproductions in book 
printing. This process has enjoyed extensive commercial success 
and is at present being used in conjunction with sound motion 
pictures. During 1930, a method was worked out of making color 
sound prints having a silver image sound track with a contrast or 
"gamma" of unity, which was claimed to result in improved sound 

In the Multicolor (two-color) subtractive process, two negative 
films are run simultaneously through any standard camera with 
their emulsion surfaces in contact. The front negative is ortho- 
chromatic, with the surface layer dyed orange-red to act as a filter for 
the image recorded on the rear panchromatic film. Double coated 


yellow dyed positive film is used for printing the pair of images in 
register on opposite sides of the film. The images are colored by a 
combined dye toning and chemical toning method and are varnished 
before projection to protect them from scratching. 

Besides the two-color subtractive processes mentioned previously, 
the following methods were enjoying some application during 1929- 
30: Color Craft, Photocolor, Sennett color, Harriscolor, and Sirius. 


Several processes have been developed for making motion picture 
prints on paper, to be projected by reflected light, but thus far no such 
motion picture color print processes are known. A great loss of light 
obviously occurs with projection of prints. 


No attempt has been made in this article to cover the subject of 
heliochromy or color photography by the use of the principles of inter- 
ference of light rays, as worked out by Lippman, Hill, R. W. Wood, 
and others. This process is very complicated and thus far has had no 
practical application. The chemistry of dyes is being extended each 
year and some simple bleach-out process may be found. 

Although three-color processes offer the only solution for complete 
and true color reproduction, a number of very pleasing two-color 
processes have been demonstrated, especially in the field of motion 

A simple process for making natural color prints still remains to be 
worked out, but methods of exposing three-color separation negatives 
have been simplified by the introduction of a screen roll film and film 
packs, as well as of a tri-pack roll film. In the professional 
field, color photography processes are being used chiefly by a few 
skilled photographers as a basis for reproductions for advertising. 
In connection with photomechanical processes, however, color 
photography has come to be used extensively. 

Motion pictures in color are now in common use, and during the 
summer of 1929 an entire feature picture in color was released with 
musical accompaniment and dialog. Color motion pictures in the 
home are also a reality, as at least two processes are known to be in 

210 GLENN E. MATTHEWS [J. S. M. P. E. 


The two most complete reference works on processes of color photography are 
the following: 

History of Three-Color Photography by E. J. Wall, American Photographic 
Publishing Company, Boston, Mass., 1925. This volume contains references to 
all literature (including patents) of color photography to the date of the publica- 
tion, exclusive of theLippmann, Seebeck, and Bleach-Out processes and of methods 
of photo-mechanical reproduction of color. 

Color Photography by W. B. Gamble and E. J. Wall, New York Public Library, 
New York, 1924. This is a list of references (1761-1923) available in the New 
York Public Library. 

Since the publication of these works, the following new books and new editions 
of books have appeared : 

Practical Color Photography by E. J. Wall, American Photographic Publishing 
Company, Boston, Mass., 1924. 2nd edition, 1928. 

Three-Color Separation Photography by G. B. Wright. Published by G. B. 
Wright, S. Norwalk, Conn., 1927. 

Color Photography by Owen Wheeler, Pitman and Sons, Ltd., London, 1928. 

Farbenphotographie by L. Grebe, A. Hiibl, and E. J. Wall, J. Springer, Berlin, 

Journal references on the subject include: the Colour Supplement of the British 
Journal of Photography included in the first week's issue of the month of this 
weekly publication; Monthly Abstract Bulletin of the Kodak Research Labora- 
tories, Rochester, New York; Photographic Abstracts published by the Royal 
Photographic Society, London, and the abstract section of Science et Industries 
Photographiques published by Revue d'Optique, Paris, France. 

Leading articles 4 on color photography which have appeared since 1925 have 
been classified as follows: 


HEYNE, W.: "The Development of Color Photography in the Past Fifteen 
Years," Phot. Ind., 23 (Sept. 7 and 14, 1925), pp. 977 and 1007. 

"The Position of Color Photography," Phot. Rund., 62 (Mar., 1925), p. 93. 

KELLEY, WM. V. D.: "Color Photography Patents," Trans. Soc. Mot. Pict. 
Eng., Nos. 21 and 24 (1925), pp. 113 and 149. 

FRISIUS: "What Is the Status of Color Photography?" Phot. Ind., 26 (1928), 
p. 497-9. 

TRITTON, F. J.: "Processes of Color Photography," Nature, 122 (Nov. 3, 1928), 
p. 687. Describes print processes. 

SHELDON, H. H.: "Color Photography," Movie Makers, 3 (Nov., 1928), p. 709. 
Describes Maxwell's experiment, Lumiere screen plates, Lippman's process, and 

ALLEN, F., AND FLEMING, A. J.: "Graphical Representation of the Stimulation 
of the Retina by Colors," Phil. Mag., 6 (1928), pp. 337-51. 

4 With a few exceptions, references to patents have been omitted from the 
bibliography. Journal references mentioned previously should be consulted. 

Feb., 1931] 



BAKER, T. T.: "The Progress of Color Photography," Discovery, 10 (Oct., 
1929), pp. 347-9. 

"Principles of Photography in Colors," Photo-Revue, 41 (Nov. 15, 1929), 
p. 345 et seq. A clear, diagrammatical explanation of additive and subtractive 

MEES, C. E. K.: "The Processes of Color Photography," /. Chem. Education, 
5 (Nov. and Dec., 1928), pp. 1385 and 1577; 6 (Jan. and Feb., 1929), pp. 44 and 286. 

CARTWRIGHT, H. M.: "The Limitations of Color Photography," Phot. J., 53 
(July, 1929), p. 323. 

GROTE, G.: "Recent Advances in Color Photography," Phot. Korr., 66 (April, 
1930), p. 91. 

BAKER, T. T.: "Measurement of Colors," Kinemat. Weekly, 163 (Sept. 11, 
1930) p. 52 et seq. 


"Jos-Pe Color Photography," Brit. J. Color Sup., 19 (July 19, 1925), p. 26. 

CROW; A. B.: "A New Camera for Color Photography," Phot. J., 67 (Mar., 
1927), p. 132. 

RENDALL, H. E.: "The Tri-Color Camera Problem, I and II," Brit. J. Color 
Sup., 21 (June 3, July 1, 1927), pp. 22 and 24. 

BOHM, H.: "The Mroz Color Camera," Kinotechnik, 10 (Mar. 20, 1928), p. 

"Repeating Back for Color Photography," Phot. J., 52 (Aug., 1928), p. 351. 

BULL, P.: "Pocket Apparatus for Three-Color Photography," Phot. J., 68 
(Nov., 1928), p. 462. Describes use of Leica camera for making color negatives 
in rapid succession. 

CHRISTOPHER, P. F.: "Cathamatics (Three-Color Filter Ratios)," Brit. J. 
Color Sup., 23 (Mar. 1, 1929), p. 9. 

"Three-Color Filter Ratios," Brit. J. Phot., 76 (Mar. 1, 1929), p. 117. The 
use of neutral density filters is recommended over the higher transmission color 

RENDALL, H. E.: "One Exposure Tri-Color Cameras," Proc. 7th Internal. 
Cong. Phot., p. 436, Heffer and Sons, Ltd., Cambridge, 1929. 

HUDNUT, I.: "A Simultaneous Exposure Three-Color Camera," Penrose's 
Ann., 32 (1930), p. 124. Describes Rene Gilbert camera. 


Three- Color Additive Processes 

Methods Using Screens 

FANSTONE, R. M.: "Screen Plates in Hot Weather," Brit. J. Color Sup., 19 
(July 3, 1925), p. 25. 

FANSTONE, R. M.: "Color Photographs by Flashlight," Brit. J. Color Sup., 
20 (Mar. 5, 1926), p. 11. 

"The Duplex Color Process," Brit. J. Color Sup., 20 (Dec. 3, 1926), p. 45. 

NINCK, A.: "Hypersensitization of Autochrome and Ordinary Plates," Bull, 
soc. franc,, phot., 13 (1926), p. 56. 

212 GLENN E. MATTHEWS [J. S. M. P. E. 

PLEDGE, J.H.: "The Lignose Film Pack and Roll Film for Direct Color Photog- 
raphy." Brit. J. Color Sup., 20 (Dec. 3, 1926), p. 48. 

MAUGE, R., AND RICHARD, A.: "Hypersensitizing Autochromes," Brit. J. 
Color Sup., 21 (May 6, 1927), p. 19. 

REICHER, L. T.: "Making Agfa Color Films," Brit. J. Color Sup., 21 (Nov. 

4, 1927), pp. 43-4. 

ROWATT, J.: "Lignose Color Process," Phot. J., 52 (1928), p. 104. 

EMMERMANN, E.: "Lignose Natural Color Films," Schweiz. Photo Ztg., 30 
(June 1, 1928), p. 194; also CHALKLEY, L., JR., Amer. Phot., 22 (1928), p. 246. 

"Commercial Screen Plate Color Photography," Brit. J. Color Sup., 22 (July 
6, 1928), pp. 25-6. 

FANSTONE, R. M.: "Instantaneous Color Photography," Brit. J. Color Sup., 

22 (Aug. 3, 1928), pp. 29-30. 

NEWENS, F. R.: "Flashlight Pictures on the Agfa Plate," Brit. J. Color Sup., 

23 (Feb. 1, 1929), pp. 5-6. 

BARROW, L.: "Exposure and Development of Autochromes," Brit. J. Color 
Sup., 23 (Mar. 1, 1929), p. 10. 

FANSTONE, R. M.: "Definition in Screen Plate Transparencies," Brit. J. Color 
Sup., 23 (Apr. 5, 1929), p. 13. 

MENTE, O.: "Improved Agfa Color Plates," Camera (Luzerne), 7 (Apr., 1929), 
p. 286. 

TALAMON, L. D.: "Supersensitizing of Autochrome Plates," Brit. J. Color 
Sup., 23 (July 5, 1929), pp. 26-8. 

GARNOTEL, R. J. : "Intensification of Autochromes by Dye Toning," Brit. 
J. Color Sup., 23 (Aug. 2, 1929), p. 29. 

JACOBSOHN, K.: "Latitude with Color Screen Plates," Das Atelier, 36 (Feb., 
1929), p. 21. 

GARNOTEL, R. J.: "Intensification of Autochromes," Photographe, 16 (Dec. 

5, 1929), p. 540. The plate is mordanted with copper thiocyanate and then 
treated with a neutral mixture of three dyes. 

ANDERSON, C. E.: "Color Photography by the Finlay Method," Bull. Phot., 
46 (May 7, 1930), p. 581. 

FINLAY, C.: "The Finlay Color Process," Phot. J., 54 (Feb., 1930), p. 76. 

GROSVENOR, M. B.: "The Color Camera's First Aerial Success," Nat. Geog. 
Mag., 58 (Sept., 1930), p. 344. Describes exposures with Finlay plates from a 

Tri-Pack Processes 

Although color prints are prepared chiefly by the following processes, the 
novelty of the process is in the use of a tri-pack method for exposing the color 
separation negatives. 

ROUSSEAU, G. A.: "A Process for Instantaneous Color Photography," Comp. 
rend., 181 (July 20, 1925), p. 110. 

ROUSSEAU, G. A.: "Instantaneous Photography of Colored Objects," Photo 
pour tous, Nos. 48, 49 (Dec., 1927, Jan., 1928), pp. 235 and 19. 

"Color Photography Commercialized," Brit. J. Color Sup., 22 (June 1, 1928), 
p. 21. Describes process of Color Photographs, Ltd. 


KLEIN, H. O.: "Progress in Color Photography," Brit. J. Color Sup., 22 
(Nov. 2, 1928), pp. 42-3. 

OLIVER, L. W. : "New Color Process of Color Photographs (British and 
Foreign), Ltd.," Phot. J., 53 (Jan., 1929), pp. 14-21. 

JOHNSON, J. D.: "Colorsnaps," Camera (Dublin), 8 (Jan., 1929), pp. 279-81. 
Dye imbibition method used for printing. 

"How Color Snapshots Are Made," Brit. J. Phot., 76 (May 10, 1929), p. 273. 

"Colorsnap Roll Film," Brit. J. Phot., 76 (May 10, 1929), p. 275. 

TRITTON, F. J. : "A Talk on the Processes of Color Snapshots (1928), Ltd.," 
Phot. J., 53 (Aug., 1929), p. 362. 

SPENCER, D. A.: "Some Fundamental Problems in Three-Color Photography," 
Phot. J., 55 (Jan., 1931), p. 9. 

Three- Color Subtractive Processes 

PERSIS, L.: "Uvachrome Color Photography," Deutscher Kamera Almanack 
17 (1926), p. 131. 

WALL, E. J.: "Titanium as a Mordant," Amer. Phot., 21 (Mar., 1927), p. 132. 

GOUD, R., "Three-Color Process for Amateurs," Photo-Revue, 39 (Apr. 1, 1927), 
p. 53. 

NAMIAS, R.: "Trichromatic Photography by Dye Toning," //. prog. Fot., 35 
(1928), p. 181. 

"Uvachrome," //. prog. Fot., 3.5 (1928), p. 302. 

HARDY, A. C., AND PERRIN, F. H.: "The Sensitometry of the Bichromated 
Gelatin Process," /. Frank. Inst., 205 (Feb., 1928), p. 197. 

GEOGHEGAN, G. : "A Simple Method for Making Three-Color Transparencies 
Brit. J. Color Sup., 22 (Nov. 2, 1928), p. 41. 

"Contribution to the History of Uvachrome," Phot. Korr., 65 (Mar., 1929), p. 91. 

RENDALL, H. E.: "Dye-Printing Processes," Brit. J. Color Sup., 23 (June 7, 
1929), p. 21. Describes Sanger-Shepherd's and Ives' Hichro (imbibition) proc- 
esses, the Raydex relief method; also Jos-Pe, Pinatype, and Dyebro processes. 

ALLISON, J. W.: "Color Photography Today," Bull. Phot., 45 (Sept. 4, 1929), 
pp. 295-300. Reviews several processes and describes cameras. 

TRITTON, F. J.: "The Theory and Practice of Three-Color Negative Making," 
Phot. J., 54 (Aug., 1930), p. 358. 

Two-Color Subtractive Processes 

"Two-Color One-Plate Process," Brit. J. Color Sup., 20 (Feb. 5, 1926), p. 7. 
Describes Mannes-Godowski process. 

NAMIAS, R.: "The Two-Color Process: Generalities Advantages over the 
Three-Color," Photo-Revue, 38 (Dec. 15, 1926), pp. 189-92. 

CHALKLEY, L., JR.: "Two-Color Transparencies," Amer. Ann. Phot., 43 (1929), 
pp. 22-31. A useful article giving complete details for preparing two-color 
transparencies by dye-mordanting methods. 


Three-Color Subtractive Methods 
General Articles 

TRAUBE, A.: "Color Photography on Paper," Phot. Ind., 26 (Dec. 19, 1928). 

214 GLENN E. MATTHEWS [J. S. M. P. E. 

pp. 1299-1300; also ibid., 27 (Feb. 20, May 22, July 10, Dec. 11, 1929), pp. 
188-9, 558-9, 736-8, 1343-5. 

Dye Toning and Chemical Toning Processes 

TURNPENNY, H. J.: "Color Photography with Transfer Papers," Amat. Phot., 
59 (May 13, 1925), p. 477. Chemical toning blue-iron; yellow-mercury; dye 

ARCH, J. C.: "Three-Color Prints by Toning," Brit. J. Color Sup., 19 (Oct. 2, 
1925), p. 37. 

LIBORA, K.: "Lage Color Prints on Paper," Brit. J. Color Sup., 21 (Jan. 7, 
1927), p. 2. 

DAIMER, J.: "The Lage Process of Color Photography on Paper," Phot. Korr. t 
63 (Aug. 1, 1927), pp. 249-50. 

McLAiN, W. S.: "Jeffery White of Detroit and His Fotocolor Process," Com- 
mercial Phot., 4 (Oct., 1928), p. 23. 

"Superprinted Three-Color Dye Mordant Prints," Brit. J. Color Sup., 22 
(Oct. 5, 1928), p. 38. 

MUDROVCIC, M.: "Experiments on a Few Three-Color Processes," Phot. 
Ind., 22 (May 29, 1929), pp. 582-4. Latter half of this paper gives directions 
for preparing positive prints by the Lage process. 

Carbon Transfer Processes 

MENTE, O.: "Color Prints by the Powder Process," Atelier, 32 (Apr., 1925), 
p. 34. 

NEWENS, F. R.: "Three-Color Carbro with a Single Bath," Brit. J. Color 
Sup., 20 (Nov. 5, 1926), p. 41. 

SCHOMMER, F.: "Color Prints on Paper by the Pigment Process," Phot. Rund., 
63 (1926), pp. 369 and 398. 

FLECK, C.: "Three-Color Albumen Process," Camera, 34 (Mar., 1927), p. 179. 

TRITTON, F. J.: "Three-Color Carbro," Phot. /., 52 (Apr., 1928), pp. 159-61. 

TRITTON, F. J.: "Practical Points in the Three-Color Carbro Process," Phot. 
J., 53 (Apr., 1929), pp. 174-9 

TRITTON, F. J.: "A Method of Increasing the Printing Speed of Dichromated 
Gelatin," Phot. J., 53 (June, 1929), p. 281. 

NEWENS, F. R.: "A New Formula and Method for Three-Color Carbro," 
Phot. J., 70 (Apr., 1930), p. 188. 

Imbibition Processes 

WHEELER, O.: "Dyebro A New Process for Making Color Prints on Paper," 
Brit. J. Color Sup., 22 (Feb. 3, 1928), p. 5. A combination of the carbro and 
pinatype processes. 

MUDROVCIC, M.: "Experiments on a Few Three-Color Processes," Phot. 
Ind., 22 (May 29, 1929), pp. 582-4. First half of this paper describes the prepa- 
ration of three-color imbibition prints. 

Color Snapshots, Ltd., use a dye imbibition process. For references, see 
section on "Tri-Packs." 

Relief Processes 

"Jos-Pe Process," Camera (Luzerne), 3 (Feb.-Mar., 1925), pp. 157 and 186. 
"The Jose-Pe Color Process," Brit. J. Color Sup., 19 (Apr. 3, 1925), p. 13. 


BOHM, G. : "Color Prints by Bromoil Transfer," Brit. J. Color Sup., 19 (June 

5, 1925), p. 21. 

"Practical Jos-Pe Procedure," Brit. J. Color Sup., 20 (Jan. 1, 1926), pp. 1-3. 

DE PROCOUDINE-GORSKY, S. : "Color Prints on Paper," Brit. J. Color Sup., 
20 (Aug. 6, 1926), p. 31. 

DEEKS, H. C. J.: "The New Deck's Process for Making Color Photographs 
on Paper," Commercial Photog., 2 (May, 1927), pp. 363-5. 

BLUMANN, S.: "Deek's Color Sheets," Camera Craft, 34 (Aug., 1927), pp. 379- 

"Duxochrome Process of Color Photography," Brit. J. Color Sup., 23 (Dec. 

6, 1929), p. 48. Color separation negatives prepared by the usual methods. 
These are printed on dyed sensitized gelatin and wash-out reliefs are obtained 
which are then superimposed. 

KENDALL. H. C.: "Dye Printing from Gelatin Reliefs," Brit. J. Phot., 76 
(Aug. 30, 1929), p. 523. 

Bleach-Out Processes 

"A Process of Direct Color Photography," Brit. J. Color Sup., 18 (Dec. 6, 
1924), p. 45. Martinez process. Silver nitrate and dyes are coated as an emul- 
sion. Exposure to light makes complementary colors developable. 

EISSFELDT, W.: "Emulsion Color Photography," Phot. Ind., 23 (Dec. 7, 1925), 
p. 1330. Colors produced after development by oxidation of leuco-bases with 
which silver halide grains have been treated. 

LUPPO-CRAMER: "Further Investigations on Obtaining Direct Positives by 
the Bleach-Out Reaction," Phot-. Ind., 24 (Jan. 25, 1926), p. 79. 

STEIGMANN, A.: "The Bleach-Out Process with Dyes and Its Significance for 
Silver Salt Photography," Phot. Korr., 62 (Mar., 1926), p. 9. 

MUDROVCIC, M.: "Sensitizers and Dyes Suitable for Bleach-Out Processes," 
Z. wiss. phot., 26 (Oct., 1928), pp. 171-92. 

HUMMEL, C.: "A New Process of Natural Color Photography by Dr. W. 
Langguth," Phot. Korr., 65 (Mar., 1929), pp. 90-1. 

Photomechanical Reproduction 

"Photogravure in Four-Color Prints," Inland Printer, 76 (Nov., 1925), p. 228. 

NEWTON, A. J.: "Photographs as Used in Color Reproduction in the Graphic 
Arts," Printing Industries, 50 (Sept., 1928), pp. 29-32 et seq. 

ROWE, D. F.: "Direct Color Photography and the Photo Engraver," Plate 
Makers' Criterion, 30 (Dec., 1928), pp. 182-3. 

BULL, A. J.: "Some Color Problems in Photo-Engraving," /. Sci. Inst., 6 
(Feb., 1929), pp. 50-1. 

TRITTON, F. J.: "The Uses of Color Photography in the Printing Trade," 
Proc. 7th Internal. Cong. Phot., p. 406, Heffer and Sons, Ltd., Cambridge, 1929. 

ARX, R. VON, "The Mordant Dye Printing Process," Proc. 7th Internal. Cong. 
Phot., p. 452, Heffer and Sons, Ltd., Cambridge, 1929. 

JOHNSON, J. D.: "Finlay Process," Camera (Dublin), 8 (July, 1929), p. 601. 
Utilizes Paget screen for making three-color separation negative from which 
three positives are prepared. Half-tone blocks are then made in the usual way. 

WHITE, J. : "Modern Color Photography Helps Produce More Business for the 
Printer," Inland Printer, 84 (Jan., 1930), p. 73. 

216 GLENN E. MATTHEWS [J. S. M. P. E. 

QUAYNB, D.: "Color Photography Its Possibilities and Limitations in 
Direct Advertising," Printed Salesmanship, 54 (Jan., 1930), p. 431. 

Two- Color Subtr active Print Processes 

RENDALL, H. E.: "Some Notes on Two-Color Photography," Brit. J. Color 
Sup., 19 (Jan. 2, 1925), p. 1. Deals chiefly with making negatives. 


General Articles 

JONES, L. A.: "Incandescent Tungsten Lamp Installation for Illuminating 
Color Motion Picture Studies," Trans. Soc. Mot. Pict. Eng., No. 22 (1925), p. 25. 

ScHWERTFtiHRER, A. VON: "Color Film Experiments," Filmtechnik, 2 (May 29, 
1926), pp. 226-8. Describes Pilney, Wolff-Heide, and Friese-Greene processes. 

PANDER, H.: "Color Degradation Caused by Moving Objects in Motion 
Pictures in Color," Kinotechnik, 8 (Aug. 25, Sept. 10, 1926), pp. 415 and 440. 

PANDER, H.: "Parallax-Free and Simultaneous Exposure," Kinotechnik, 8 
(Sept. 25, Oct. 10 and 25, 1926), pp. 471, 495, 516. 

PANDER, H.: "Space and Time Parallax," Kinotechnik, 8 (Nov. 25, Dec. 10 
and 26, 1926), pp. 572, 603, 628. 

TROLAND, L. T.: "Some Psychological Aspects of Natural Color Motion 
Pictures," Trans. Soc. Mot. Pict. Eng., XI, No. 32 (1927), p. 680. 

CRESPINEL, W. T.: "Color Photography," Amer. Cinemat., 9 (Mar., 1929), p. 4. 

NAMIAS, R.: "Color Cinematography," Internal. Review Educational Cinemat. 
1 (Aug., 1929), p. 175 et seq. 

HUSE, E.: "Nature of Color," Internal. Phot., 1 (Sept., 1929), p. 31. 

Three- Color Additive Processes 

SPANUTH, H., AND HOHNHOLD, R. : "Camera and Projector for Motion Pictures 
in Natural Colors (according to Szczepanik)," Phot. Korr., 61 (1925), pp. 12-21; 
also Kinotechnik, 7 (Apr. 10, 1925), p. 157. This process uses a continuously 
driven camera and projector. 

SZCZEPANIK, J.: "Cinematography in Natural Colors," Brit. J. Color Sup., 
19 (Oct. 2, 1925), p. 38. 

RAGUIN, G.: "Raguin Process of Photography and Cinematography in Color," 
Bull. soc. franq. phot., 13 (June, 1926), p. 158. 

NACK, E. W.: "The Horst Color Film," Filmtechnik, 2 (Aug. 21, 1926), pp. 

BOURQUIN, H.: "Color Cinematography by the Wolff-Heide Process," Phot. 
Korr., 64 (June 1, 1927), p. 186. Pictures exposed at 28 frames per second on 
film, every alternate frame of which is sensitive to red and blue, respectively. 
Alternate frames of print dyed and film projected 28 frames per second. (Later 
changed to three-color process; print frames dyed red, blue, and yellow, re- 
spectively. Projected with continuous projector. Report of the Progress 
Comm., /. Soc. Mot. Pict. Eng., 15 (Dec.. 1930), p. 759.) 

POWRIE, J. H.: "Line Screen Film Process for Motion Pictures in Color," 
Trans. Soc. Mot. Pict. Eng., XH, No. 34 (1928), p. 320. 

CAPSTAFF, J. G., AND SEYMOUR, M. W.: "The Kodacolor Process for Amateur 

Feb., 1931] 



Color Cinematography," Trans. Soc. Mot. Pict. Eng., XII, No. 36 (1928), pp. 

RODDE, M., "The Herault Trichome Process," Bull. soc.franq. phot., 15 (Mar., 
1928), p. 80. Successive frames tinted and film projected 24 pictures per second 
on a continuous projector. 

MEES, C. E. K.: "Motion Pictures in Natural Colors," Camera Craft, 35 
(1928), pp. 303-5. Describes Kodacolor process. 

"Keller-Dorian Color Film System," Licht Bild Buhne, 21 (Oct. 6, 1928), pp. 

ANTHONY, E. C.: "Vitacolor Movies," Movie Makers, 3 (Dec., 1928), p. 771. 

MEES, C. E. K.: "Amateur Cinematography and the Kodacolor Process," 
/. Frank. Inst., 207 (Jan., 1929), pp. 1-17. 

CORY, A. B.: "The Kodacolor Process," Amer. Ann. Phot., 43 (1929), pp. 9-11. 

"Third Dimension hi Colored 'Talkies,' " Photo Era, 63 (Aug.-Sept., 1929), 
pp. 103, 162. Rotating sector wheel used in exposing pictures alternately in 
camera. Ordinary positive print projected onto composite perforated metal 
screen made up hi four layers, each of a different color. 

HATSCHEK, P.: "Color Film Using Embossed Prisms," Filmtechnik, 5 (Apr. 13, 
1929), p. 154. Exposure is made through the base side of a film embossed with 
minute prisms, each of which forms a spectrum on the emulsion. Projection is 
made after the images have been developed by reversal. No filters are used in 
either the camera or projector. 

TUTTLE, H. B.: "Some Experiments in Medical Motion Pictures in Color," /. 
Soc. Mot. Pict. Eng., 15 (Aug., 1930), p. 193. Describes lighting equipment for 
making Kodacolor pictures of surgical cases. 

"New Three-Color Process," Kinemat. Weekly, 155 (Jan. 9, 1930), p. 25. 
Describes Horst system in which three pictures are exposed simultaneously with 
the aid of a prism arrangement. In the positive each frame carries three images. 

Two-Color Additive Processes 

FRIESE-GREENE, C. H.: "The Friese-Greene Color Process," Phot. J., 49 
(1925), p. 487. 

FRIESE-GREENE, C. H. : "Color Cinematography by Photographic Impression/' 
Bioscope Sup., 67 (Apr. 29, 1926), p. III. 

MARTIN, K.: "The Color Film of E. Busch Akt.-Ges. hi Rathenow," Phot. 
Korr., 63 (Jan. 1, 1927), p. 12. 

BOURQUIN, H.: "New Film hi Natural Colors," Der Bildwart, 5 (July, 1927), 
p. 432. Alternate pictures dyed red and green, 

LEHMAN, E., AND KOFES, A.: "Possibilities of Two-Color Photography," 
Kinotechnik, 9 (Aug. 5 and 20. 1927), pp. 397 and 428. Comparison of additive 
and sub tractive processes. 

NAUMANN, H.: "The Busch Two-Color Film hi the Service of Medicine," 
Phot. Korr., 65 (April, 1929), p. 117. 

STEINER, J.: "Color Cinematography according to H. May's Process," Phot. 
Korr., 65 (May, 1929), p. 149. Rotating sector wheel used before the camera 
and projector. 

TIETZE, P.: "An Apparatus for Color Cinematography for the Purposes of 
Medical Instruction," Internal. Review Educational Cinemat., 1 (Sept., 1929) 

218 GLENN E. MATTHEWS [J. S. M. P. E. 

p. 270; also Kinotechnik, 11 (Feb. 20, 1929), p. 99. A description of the Busch 

EGROT, L. G.: "Raycol Process," Kinemat. Weekly, 152 (Oct. 10, 1929), p. 
63. Two images are exposed simultaneously by means of a prism beam splitter. 
Images occupy diagonally opposite corners of a standard frame and are one- 
quarter normal size. The black and white positive is projected through a special 
lens system which superimposes the images on the screen; only one image (the 
red sensation) is projected through a filter, the other being projected in black and 

EGROT, L. G.: "Busch Color Process," Kinemat. Weekly, 152 (Nov. 7, 1929), 
p. 52. Film runs horizontally through a camera fitted with a prism beam splitter. 
Images are one-half normal size, one above the other on each standard frame. 
Images are projected through separate lenses and appropriate filters, and are 
superimposed on the screen. 

Three-Color Subtr active Processes 

"Thornton Three-Color Cinematography," Brit. J. Color Sup., 20 (Feb. 5, 
1926), p. 8; also ibid. (July 2, 1926), p. 28. 

BENNETT, C. N.: "Zoechrome," Bioscope, 72 (Aug. 11, 1927), pp. 9-10; also 
Kinemat. Weekly, 132 (Mar. 21, 1929), pp. 69-70. Every other negative frame 
is a regular black and white exposure ; alternate frames have three small pictures 
( 3 /4 standard size) exposed through red, blue, and yellow-green filters. Black 
and white negative printed and developed; film varnished and recoated with 
emulsion; each small image printed in register and dye toned. 

"The New Three-Color System," Kinemat. Weekly, 144 (Feb. 21, 1929), 
p. 58. Describes Splendicolor Process. 

Two- Color Subtr active Processes 

RIGHTER, F. L.: "Chemical Engineering and the Motion Picture Industry," 
Chem. Met. Eng., 32 (July, 1925), p. 627. Describes Technicolor Laboratories 
in Hollywood. 

"Two-Color Cinematography by Metallic Toning," Brit. J. Color Sup., 19 
(Nov. 6, 1925), p. 43. Describes Kelly-Color Process. 

EVELEIGH, L.: "Technicolor," Bioscope Sup., 66 (Jan. 21, 1926), p. III. 

IVES, F. E.: "Subtractive Color Motion Pictures on Single Coated Film," 
Trans. Soc. Mot. Pict. Eng., No. 25 (1926), p. 74. A review of several processes. 

KELLEY, WM. V. D.: "Imbibition Coloring of Motion Picture Films," Trans. 
Soc. Mot. Pict. Eng., No. 27 (1926), p. 238. 

"Technicolor Films and Their Projection," Bioscope, 81 (July 17, 1926), p. 189. 

N AMI AS, R. : "The Application of the Two- Color Process to Cinematography," 
El. prog, fot., 8 (May-June, 1927), pp. 103 and 132. 

KNOCHE, P.: "New German Two-Color Films," Kinotechnik, 9 (Nov. 20, 
1927), p. 596. 

IVES, F. E.: "Something More about Progress in Subtractive Process Cinema- 
tography," Trans. Soc. Mot. Pict. Eng., XI, No. 30 (1927), p. 211. 

JONES, L. A., AND TUTTLE, C.: "The Reproduction of Mobility of Form 
and Color by the Motion Picture Kaleidoscope," Trans. Soc. Mot. Pict. Eng., 
XII, No. 33 (1928), p. 140. 


"Polychromide Color Process," Bioscope, 77 (Oct. 17, 1928), p. X. Describes 
Hamberger's process. 

"Pathechrome Process," Ex. Herald-World, 93, Sect. 1 (Nov. 24, 1928), p. 34. 

"Color Camera Making Rushed to Get Set for Increased Use Next Season," 
Ex. Herald-World, 96 (July 6, 1929), p. 70. Describes new two- or three-color 
Technicolor process; also some data on Pathechrome process. 

"Sirius Color Film," Licht Bild Bilhne, 22 (Aug. 17, 1929), p. 14. Two-color 
negatives exposed with the use of a prism beam splitter system. Positives 
printed on opposite sides of double coated film and pictures are dye toned. 

CRESPINEL, W. T.: "Illustrating Multicolor," Internal. Phot., 1 (Aug., 1929), 
p. 30. 

BROWN, G. B.: "Color Camera Outdoors," Internal. Phot., 1 (Sept., 1929), 
p. 34. Describes the making of an all outdoor picture by the Technicolor Process. 

STULL, W.: "Multicolor Introduces Improved Color Film," Amer. Cinemat., 
10 (Dec., 1929), p. 9. 

Fox, D.: "Ninety Million Feet of Color Photography Set as Color Craft 
Yearly Output," Ex. Herald-World, 98 (Jan. 4, 1930), p. 26. Two negatives used 
emulsion to emulsion in exposing film and double coated positive film for making 
the prints which are subsequently dye toned. 

BAKER, J. L.: "Color of the Future," Internal. Phot. Bull., 11 (Feb., 1930), 
p. 13. Describes Photocolor process. Negatives are made with a twin lens 
camera and positives are dye toned on double coated film. 

PECK, A. P.: "Movies Take on Color," Sci. Amer., 142 (Apr., 1930), p. 285. 
Short illustrated article on Photocolor process. 

"Report of the Color Committee," /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), 
p. 721. Describes Colorcraft, Multicolor, Harriscolor, Technicolor, and Sennett- 
color processes. 



Summary. The development of sound motion pictures, utilizing electrical repro- 
duction of sound, has caused a convergence of the technic of radio broadcast trans- 
mission and reception and the technic of the- sound motion picture studio and theater. 
The approaching advent of home sound motion pictures and television broadcasting 
may be expected to bring the engineering methods still closer together. 

Paralleling this engineering approach, there are indications of a similar and 
cooperative integration of the corresponding industries. The establishment of a great 
entertainment center in New York City, based on this evolutionary plan, is described 
in the paper. In this "Entertainment City" are to be combined radio broadcasting 
studios, recording facilities, auditoriums, executive offices of corresponding entertain- 
ment enterprises, and a group of large theaters and concert halls of various types. 

The scope of a great industry tends ever to broaden. To this 
rule, the motion picture industry is no exception. It is being brought 
into touch with industry through the industrial picture, with the 
school through the educational picture, and with the home, through 
the rental library of entertainment films. And now contact has also 
been established between motion pictures and radio, through the 
laboratory development of television. It seems as if a considerable 
portion of the telephone and television programs of the future will 
originate on sound motion picture films, thus opening a great new 
field for the motion picture industry. Cooperation between motion 
pictures and radio has already led to one concrete plan of amazing 
magnitude in which these arts will be developed and exhibited in a 
"city" to be shortly created. 

New York, within a few years, will be the proud possessor of a 
city within a city, popularly called the "Radio City." This city a 
great community dedicated to the thought that the appreciation of 
art dwells in the people, and that the mass dissemination of art, 
education, and entertainment, is one of the greatest constructive 
functions of a modern democratic civilization will rise in the center 
of New York. 

* (Abridged.) Presented at the Fall 1930 Meeting, New York, N. Y. 
** Radio Corporation of America, New York, N. Y. 


The public is already aware of the group of organizations and lead- 
ers of thought associated in this enterprise. This assembly of gigantic 
buildings, with private streets, plazas, transportation facilities, 
and similar features, is to be erected through the planned cooperation 
of Mr. John D. Rockefeller, Jr., and the Radio Corporation of America 
and its subsidiaries. The group of companies involved will have 
their headquarters in these buildings, and there will be an unprece- 
dented concentration of facilities for the dissemination of sight and 
sound by radio and by record through the air, the film, and the 

In the new Entertainment City, the plans of which can now be 
more readily considered, Radio Keith Orpheum will have a sound 
motion picture theater, variety theater, musical comedy theater, 
and a dramatic theater. The National Broadcasting Company will 
have studios adapted for service to its radio networks. The RCA 
Victor Company and RCA Photophone will have auditoriums, 
projection rooms, and other facilities necessary for sound recording 
for home and theater, respectively. Various miscellaneous radio 
and sound recording and reproducing facilities will exist, in addition 
to, perhaps, a great symphony hall, in which concerts by leading 
orchestras may be given to the public, not only by broadcasting, 
but to an actually present audience. 

In this group of buildings there will be concentrated facilities for 
radio telephony, radio facsimile, radio television, and the recording 
and reproduction of sound and pictures. 

A city of this sort must rest on a solid scientific foundation. Back 
of its activities must be research men, investigators, development 
engineers, and extensive laboratories. The products of the toil 
of all these men are necessary to keep such a city in the forefront 
of artistic as well as scientific progress. The coordination of science 
and art toward a single aim the welfare of mankind will be illus- 
trated in an unusually fine form. 

As a sociological experiment, it is believed that the Entertainment 
City will be watched with close attention by careful students of 
public affairs. Through the Entertainment City the artists may 
spread their inspiration before the multitude for acceptance or re- 
jection, as the world may determine. Artists whose wage is too high 
for the entertainment of small audiences, artists of difficult tempera- 
ment or with an aversion to travel, artists, who, for all the usual 
reasons would be unavailable to the majority of the people, may 


reach the individual in any part of the nation. The Entertainment 
City may, in fact, serve as a model of an artistic and cultural nu- 
cleus for many of the cities of the future. What the effects of such 
a project will be on architecture is a fruitful subject for speculation. 
As time goes on, the world's workers will presumably find increasing 
leisure. The successful utilization of leisure is a major problem, 
toward which the Entertainment City contributes at least a portion 
of the answer, in addition to contributing to the general cultural 
level of the people. 

Doubters will ask whether humanity can indeed assimilate and 
appreciate all that will be offered to it. Presumably we must not 
look for a Utopia of today and tomorrow. However, unless human 
evolution and progress are the pathetic dreams of self -deluded weak- 
lings, a community of art serving the planet and the nation will be 
in considerable measure constructive and helpful, uplifting and 
inspiring to the people of the world. 

We of today can hardly judge the full meaning of the City of 
Art. Looking backward a century, the historians of a hundred years 
later will understand better than we of today, how basic a step has 
been taken. Perhaps there are giants among us in these days as 
in the past. Romance, determination, and courage are not dead 
when such a project can be brought into being. New frontiers of 
achievement glow before the founders of the Entertainment City 
to inspire them to push onward in this great experiment to which 
they have dedicated their best effort. * 

Such a project should hold the attention of all of us who are motion 
picture engineers. As scientists and engineers, we are giving our 
best to the service of humanity. Ours is not the reward of fame, 
with its flaming letters of light in a thousand cities. Ours is not 
the recompense of fabulous wealth which is lavished on the studio 
favorites of the nations. But better yet, and of far more enduring 
worth, is our opportunity, through wisdom and skill, through con- 
tinued intelligent and directed work, to be at once the true servants 
and the inspired leaders of humanity to bring joy into countless 
lives through our toil and through our effort, in the truest and finest 
sense, to help a grim and saddened world, and "to brighten the 
corner where we are." 




OCTOBER 22, 1930 

PRESIDENT CRABTREE: Our Society chose to convene in New 
York City this fall with the deliberate object in view of effecting a 
closer relationship between ourselves and those who are producing 
motion pictures. New York City is destined to become increas- 
ingly important as a production center and it is to the interest of our 
members to become as fully acquainted as possible with the problems 
of the producers. On the other hand, it is to the interest of the pro- 
ducer that he keep abreast of the achievements of the scientists 
and technicians, who, in the first place, made motion pictures pos- 
sible, who made the shadows talk, and upon whom the industry will 
have to rely to an increasing extent to feed the insatiable appetite 
of the public for something different in entertainment. 

Our Society was founded in 1916 by Mr. C. Francis Jenkins of 
Washington, D. C., with three objects in view: (1) the advance- 
ment of motion picture engineering and the allied arts and sciences; 
(2) the standardization of the mechanisms and practices employed 
in the motion picture industry; and (3) the dissemination of scien- 
tific knowledge by publication. The new Society began to hold 
semi-annual conventions, at which technical papers were read and 
discussions invited, and this scientific information was published in 
the quarterly Transactions of the Society. These appeared in un- 
broken succession until January, 1930, when they were superseded by 
the monthly JOURNAL. 

Our Society contains about 1000 members having diversified in- 
terests and qualifications, including research scientists from the 
universities and industrial research laboratories, practical engineers 
from the factories, studios, laboratories and theaters, and executives 
from all branches of the industry. 

I am afraid that the term "engineer" has, in the past, frightened 
a number of otherwise eligible persons from. joining our Society. We 



interpret the word to apply to anyone who contributes to the build- 
ing of a motion picture, so that there is no reason why those who 
contribute literary, dramatic and artistic talent should not become 
members of the Society, as well as those who direct the business of 
production and distribution of motion pictures. 

Few persons realize the complexity of the motion picture organ- 
ism, which is dependent for its existence on more of the arts and 
sciences than any other industry with which I am acquainted. No 
artistic conception of author, dramatist, director, or actor can be 
given to the public through the medium of the motion picture except 
by the application of chemistry and physics which, in turn, embrace 
heating, lighting, acoustical, mechanical, and electrical engineering. 
The manufacture of the film itself requires a knowledge of all these 
sciences as well as a knowledge of the nature of light. The cameras, 
arc and camera silencing devices, lighting and sound recording equip- 
ment used in the studios, and even the make-up for the actors, are 
the result of the combined efforts of almost every type of engineer 
and research worker in existence today. The development of the 
film in the laboratories to produce images in black and white and in 
color was made possible by the concentrated efforts of chemists and 
physicists. It is only as a result of intensive effort on the part of the 
research laboratories devoted to photography that it has been pos- 
sible within the past year to develop the film with the scientific 
precision necessary for sound films. The construction and use of 
the machinery for projection requires the application of mechanical, 
electrical, and optical principles, while the modern theater is a scien- 
tific structure requiring the application of all the above sciences, in- 
cluding acoustical engineering. 

In such a complex structure involving so many personalities, it 
is necessary that all the component parts should work in harmony. 
Those concerned with artistry should encourage the research and prog- 
ress which is necessary to present their art most effectively to the 
public, while the engineer should remember that his instruments 
are only a vehicle for presenting the creations of the artist to the 

Membership in our Society is of four types: Associate, Active, 
Sustaining, and Honorary. Any one who is interested in motion 
pictures is eligible for Associate membership. Active membership 
is granted to those who have gained distinction in their particular 
field of endeavors. Sustaining members are those who contribute 

Feb., 1931] BANQUET SPEECHES 225 

substantially to the support of the Society, while Honorary member- 
ship has been granted to those scientists of international fame who, 
by their inventions and achievements, have been largely responsible 
for the building of this great industry. 

Committee work is the backbone of the activities of any technical 
society. Our standing committees are composed of the best experts 
in their particular field, and deal with Color, History, Progress, 
Projection, Sound, Standards, and Theater and Studio Light- 

We have local sections in New York, Chicago, London and Holly- 
wood which foster a spirit of cooperation among the members who 
cannot always attend conventions of the parent society. The 
Hollywood section keeps the parent body in touch with production 
activities on the West coast and maintains contacts with the Academy 
of Motion Picture Arts and Sciences. 

We are proud of our accomplishments during the past fourteen 
years. Our Transactions and JOURNAL represent the most compre- 
hensive source of motion picture technical information in the world. 
The potential value of this knowledge to the industry is incalculable 
and the actual cost of the research work required to obtain it amounts 
to billions of dollars. It may be of interest to note that the advan- 
tages of optically reducing a picture on wide film down to 35 mm. 
film were outlined and practically demonstrated before our Society 
and recorded in our Transactions in the year 1924. 

The bi-annual report of the Progress Committee gives, in condensed 
form, the essential technical developments in the fields of production, 
distribution, and exhibition throughout the world. The Society, 
through its Standards Committee, has made possible the interchange- 
ability of the essential parts of apparatus throughout the industry 
and has published details of these in booklet form in collaboration 
with the American Standards Association. The Society has also 
collaborated with the British, French, and German technical socie- 
ties on all matters relating to standards. 

The specific problems of the producer have also received their 
fair share of attention. Improvements in microphone placement, 
the increasing use of single microphones, remote control, and methods 
of dubbing have resulted in many cases from the stimulation of ideas 
received from discussion at the Society meetings. The Studio Light- 
ing Committee has assembled information on the use of exposure me- 
ters in the lighting of sets, and tests to date have indicated that a con- 


siderable saving of electrical energy would result from the intelligent 
use of photometers. 

The most outstanding efforts of the Society in relation to pro- 
duction have been an attempt by the Standards Committee to 
arrive at a standard for wide film. 

It is quite generally agreed that placing the sound track on the 
present 35 mm. film results in a picture having undesirable propor- 
tions. When these proportions are corrected by masking the height, 
the smaller picture area requires greater magnification of the film in 
order to cover the same size of screen. As the magnification has al- 
ready been pushed close to the limit set by the graininess of the film, 
the utilization of a portion of the film for the sound track has made the 
projection of pictures of even moderate screen dimensions not alto- 
gether satisfactory. Simultaneously with the general introduction of 
sound has come a desire on the part of the industry for a large pro- 
jected picture which will include more action. Although several 
methods have been suggested for the realization of large screen pic- 
tures using the present 35 mm. film, the committee feels that none of 
these methods offers a permanent solution of the problem. At the 
present time, the only satisfactory method of obtaining a large screen 
picture having a width of 30 to 40 feet seems to be through the use 
of a wider film. 

In considering a new standard for wide film it is obvious that any 
practical recommendation must involve the ratio of screen width to 
screen height that is already established within reasonably narrow 
limits by both the proscenium arch and the balcony cut-off in exist- 
ing theaters. An investigation of this subject shows that, whereas 
a few of the larger theaters can use a ratio of width to height as great 
as 2 to 1, the ratio for the smaller theaters is usually less. After 
careful consideration of this subject, the Standards Committee 
has recommended the adoption of a 1.8 to 1 ratio of width to height as 
the best compromise. This ratio seems to be not out of line with 
prevailing sentiment among members of the Academy of Motion 
Picture Arts and Sciences, with whom the matter will be discussed 

Having established a maximum height to width ratio for the pic- 
ture frame, it is necessary to decide on the minimum width of film 
necessary to insure good sound and picture quality. Anything 
wider than this minimum would be an economic waste, which must 
be prevented at all costs. 

Feb., 1931] BANQUET SPEECHES 227 

During the deliberations of the committee, it became increasingly 
evident that the adoption of release prints with a width in the neigh- 
borhood of 65 or 70 mm. would be economically impracticable for a 
large proportion of theaters. It seemed desirable, therefore, to give 
consideration to a film size intermediate between these dimensions 
and the present 35 mm. standard. The committee is working on a 
layout that will permit the use of 1.8 to 1 ratio and provide for a 
wider sound track with more suitable margins, and is attempting 
to assign dimensions to this film that will permit the most economic 
use of existing 35 mm. equipment. 

While the specifications of the release print dimensions is the prob- 
lem of most importance, the Standards Committee has under con- 
sideration a negative of such proportions that it may be printed by 
optical reduction on to 35 mm. film or on the new intermediate film or 
by contact on a large film for de luxe houses. 

During our technical sessions consideration was also given to the 
various advantages and disadvantages of placing the picture and 
sound record on separate films. From the discussion it was revealed 
that such a procedure may ultimately be desirable and even im- 
perative. Such a step, however, would not involve scrapping present 
equipment, but would necessitate additional mechanisms. 

But how can better coordination between ourselves and the pro- 
ducers be assured? The Technicians Branch of the Academy, spon- 
sored and subsidized by the production interests, is coordinating 
technical effort in Hollywood, disseminating technical knowledge by 
publication, and standardizing practices. The standard release print 
is a worthy accomplishment. The Academy and our Society must 
work more closely together to insure a minimum duplication of 

Our Board of Governors has approved that a section of our JOURNAL 
be reserved for a digest of the activities of the Technicians Branch of 
the Academy, and has authorized me to discuss with the Academy, 
ways and means of effecting further collaboration. 

To date, however, the Academy has been concerned with practi- 
cal application and not with pure research, which, as I have pointed 
out, is vitally necessary for the future growth of the industry. We 
need more research, more laboratories, more man. power trained in 
thinking scientifically. Before the problem of television is solved, 
so the picture becomes large and clear and rendered in color like 
the present picture in the theater, some new fundamental scien- 


tific discovery will have to be made, and even then the problem will 
be solved only by the combined efforts of many workers. It is to 
the interest of all branches of the industry to encourage and to con- 
tribute financially, to insure a steady flow of new fundamental dis- 

You producers can contribute to the welfare of our Society and 
the industry by intensifying your interest in technical matters, by 
encouraging your employees to become members of our Society, to 
subscribe to our JOURNAL, to take an active part in Society affairs, and 
to permit them to spend a portion of their working hours in the in- 
terests of our Society. The slight expense involved in sending 
representatives to our conventions will be repaid a hundred-fold by 
virtue of the stimulation of ideas in your personnel. These men will 
make new friends and get in touch with experts who are ready, at 
all times to aid in solving your individual problems, either by corre- 
spondence or by personal contacts, and their value to you will be en- 
hanced accordingly. The usefulness of the Society in this respect, 
like that of a telephone exchange, increases as it grows in size. 

You can also cooperate in a practical way by becoming sustaining 
members of the Society. To date, all executive work has been 
carried out voluntarily by Society members employed by certain of 
the large manufacturing organizations, but each concern should 
shoulder its fair burden. With the aid of paid executives it will be 
possible to widen the field of usefulness of our Society to the industry 
by serving as a clearing house for motion picture engineering data, 
by expanding the work of standardization, by maintaining closer 
coordination with allied technical and scientific organizations, and 
by assisting in the establishment of courses in motion picture engi- 
neering in some of the Eastern universities, thereby helping to fill the 
ranks of the producers with trained employees and potential execu- 
tives having an adequate grounding in fundamental principles. 

We must not lose sight of the fact that the main problem of the 
producer of motion pictures is one of dramatics he is constantly 
striving to incorporate in that small film image the intangible some- 
thing which will tickle the emotions of the theater patron. The pub- 
lic is always looking for something new and different; since the 
drama has changed very little in the past three hundred years the 
producer must depend more and more on the engineer to add novelty 
to his presentation. 

We engineers realize that the quality of the sound as reproduced 

Feb., 1931] 



in the average theater must be improved if the public is to remain 
interested. The quality of speech is satisfactory, but that of music 
leaves much to be desired. The public has become educated to the 
finer points of musical quality as a result of better radio reception. 
We must keep ahead of this standard of public appreciation if the 
sound is to provide a sufficient emotional stimulus. However, with 
existing film and equipment it is possible to record and reproduce 
sound with a much greater degree of realism than is manifest in many 
theaters today. The remedy for this is the education of all those 
responsible for the handling of the film, not forgetting the theater 

No effort must be spared to improve sound quality even if this 
requires wider film or involves placing the sound record on a separate 
film. As compared with a train load of impedimenta required to 
stage a traveling dramatic show, what does it matter if an extra pro- 
jection machine, an extra film, or an extra projectionist be required 
to insure the utmost in entertainment? The industry must face the 
fact that it will constantly have to improve the various mechanisms 
employed, if the interest of the public is to be maintained. 

We, the members of the Society of Motion Picture Engineers, 
pledge ourselves to give increasingly of our services and knowledge, 
with a view to adding realism to the motion picture, thereby contrib- 
uting to the education and enjoyment of the theater patrons through- 
out the world. 

I have tried to stress the importance of research. We are now to 
hear from a member of our Society, the vice-president and general en- 
gineer of one of the large organizations which is concerned not only 
with the production, but with the exhibition, of motion pictures Dr. 
Alfred N. Goldsmith, Vice-President of the Radio Corporation of 

DR. GOLDSMITH: One of the first researches, perhaps the great- 
est research, carried out by mankind, occurred when some primi- 
tive individual stuck his fingers into a yellow flame which had some- 
how been produced, and withdrew them with a howl. He had a 
sense of curiosity which was unpleasantly gratified. Neverthe- 
less, protection against wild animals, and cooked food were the first 
results. The further results during the millennia which have passed 
since that memorable day fairly stagger the imagination by their 


Presumably it is fair to state that man and his lowly cousins, the 
apes, are distinguished from the rest of the animal kingdom by an 
amount of curiosity which is sometimes rather unhealthy. Men and 
monkeys get into all sorts of difficulties by trying this and that by 
"monkeying with it," as we say. Nevertheless, men accomplish a 
great deal in just this way. Curiosity is perhaps the greatest single 
force in the advancement of mankind and has done more to contrib- 
ute toward the evolution of science, engineering, and industry in 
general than any other single factor. 

The great creed of industry today has two sections. The first of 
these is, "study the possibilities." The second one is, "try them out." 
Each of these involves research. Research is simply organized 
curiosity. Research may be scientific or it may be industrial, but it is 
research just the same. 

Modern research differs from the earlier random and haphazard 
experiments in that it is in general more definitely directed and far 
better organized. If one carries out research on almost anything 
that happens to pop up in one's head, one may hit a desirable target 
perhaps once in a million times, but if research is intelligently 
directed along apparently promising lines, one may hit the target once 
in a hundred times and this is about the "batting average" of a 
succcessful research man. 

The careful organization of research and the provision of suitable 
equipment and favorable surroundings are extremely necessary. 
Trying to think things out in a garret without any equipment while 
freezing to death is all very well in its way. It is a romantic and 
picturesque procedure (at any rate for the people who read the life 
story of the dead inventor). But providing a large staff of highly 
skilled men for research, and supplying them with proper quarters 
and modern apparatus is much more likely to lead to early and worth- 
while results. 

Industry ever develops from the simple toward the complex. Its 
scope first extends from a mere locality to a city, then to a state, a 
nation, and finally to the entire world. It cannot meet the pressing 
needs of mankind on such a vast scale except through unremitting 
toil in the finest laboratories. Pure scientists, application engineers, 
and commercial investigators are clearly a part of the successful 
business structure of the present and future. Industry will encourage 
research lest it stagnate and perish. The specter of obsolescence 
always faces the industry that does not enthusiastically foster research. 

Feb., 1931] BANQUET SPEECHES 231 

Much has been achieved in the motion picture field through re- 
search up to the present, but far more astonishing possibilities, in a 
multitude of new directions, shine brilliantly before us, awaiting 
only the skill of the research specialist to bring them into the world 
of actual things. Men will continue their everlasting battle against 
ignorance. They will gather, as the fruit of their toil, the precious 
knowledge which is power. Modern machinery will release them 
from excessive toil, and the future entertainment devices, which will 
use scientific methods to get artistic and entertaining results, will 
brighten their hours of leisure. Through research, men arrive at the 
truth concerning nature and bend natural forces to their will. 
Through research there will be fulfilled the ancient prophecy: "For 
ye shall know the truth, and the truth shall set ye free." 

PRESIDENT CRABTREE: We all like to know what the other fellow 
is doing. The Vice-President of our Society recently returned from 
England and I am sure our producer- guests would like to hear some 
of his impressions Dr. K. Hickman. 

DR. HICKMAN: Mr. President, Ladies and Gentlemen, and Dis- 
tinguished Guests: We are here tonight to honor the producer. The 
other speakers will tell you of the many wonderful things the pro- 
ducer has accomplished in the last thirty years ; I will relieve the dull 
monotony of praise with the mildest of mild criticisms. 

What has the producer accomplished in sound, for instance? 
We can remember going to the movies twenty years ago and hearing 
the tinkling of a piano, to which tune Bronco Billy lassoed a bucking 
steer. At the end of each reel the tinkling stopped, the couples in 
the back row unclasped, the lights went up, a brief pause, and then 
more picture and more tinkling. Even in those early days, music 
was recognized as an essential part of the presentation. 

From the tinkling piano we graduated to the trio, to the orchestra, 
to the full symphony orchestra, and now, in the fullness of time, to 
that magnificent achievement, "sound-on-film," where the musical 
art of four hundred years is crowded into a strip one-eighth inch wide 
and the art of thirty years occupies a full inch, and the scientist-pro- 
ducer is proud. But why stop there? You have brought the sym- 
phony concert to the movies why not the movies to the symphony 
concert? That would be doing a real service to humanity. 

The ideal music for a picture has been described as pleasant to 
the ear but having no definite theme to distract the mind. I suppose 


the ideal picture for a classical concert would be pleasing to view but 
have no story to claim the attention. You will agree with me that 
research is hardly necessary here just use any current release. 

Just another thought before I sit down how about giving the 
poor public the right of choice? When you enter a shop to buy 
socks you can weigh your money in one hand and size up the socks 
with the other, and take the variety you want. When we enter a 
theater you take our money at the door, and if afterward we don't 
like the show there is nothing we can do about it but stare at the 
ceiling. With the picture growing larger month by month there is 
less and less of the theater left to test one's eyes. If you had your 
patrons' welfare really at heart you would provide a different show 
at each end of the house, and swivel chairs, and let the social conse- 
quences take care of themselves. 

PRESIDENT CRABTREE: We shall now hear from the man who 
directs the operations of the largest research laboratory in the world, 
Mr. H. B. Charlesworth, Vice- President of the Bell Telephone Labo- 
ratories, Inc. 

MR. CHARLESWORTH: I simply want to say how pleased I am to 
be with you tonight and that our organization has been glad to 
participate in the deliberations of this Society whose work is so far- 
reaching and important in the industry. We all know what an im- 
portant part research is playing in industry. The time has long 
since passed when a cut and dried method is going to carry us through ; 
how true that is of the motion picture industry, which is concerned 
with so many elements requiring fundamental research for their 
solution. We are glad to have had a part in the development of the 
motion picture industry and hope that we shall contribute our full 
share to its development in the future. 

It would be only repetition to outline some of the interesting prob- 
lems before us. We know that future progress will be bright, and 
I shall not take further time to deliberate about it. I thank you for 
the privilege of being with you. 

PRESIDENT CRABTREE: Our next speaker is known to all of you. 
I venture to say his name is known to every man, woman, and child 
in the country. He wields a guiding hand over the destinies of 
this industry; he is not unmindful of our activities, as manifested 
by the stirring speech he made at our last convention. He has kindly 

Feb., 1931] BANQUET SPEECHES 233 

consented to introduce the various producers and guests this even- 
ing Mr. W. H. Hays, President of the Motion Picture Producers 
and Distributors of America, Inc. 

MR. HAYS: In a world where industry literally must keep its 
eye on the keyhole of the laboratory if it is to endure, and where 
what happens in a test-tube may very probably entirely obliterate 
the art and put a new one in its place, I don't have to emphasize 
the importance of your activities to the motion picture industry. 
It is a great satisfaction to be able to contact with those whose busi- 
ness, mainly precise discovery, is not affected at all by what may be 
the psychological condition of a people and an imaginary or so-called 
depression which appears to be upon us. 

I was very interested in the speech by your Vice-President. He 
spoke of the "tinkling" which has always been with the movies. 
About twenty-five years ago that started. A merchant from a small 
town in Wisconsin walked into a theater somewhere in a side street 
in Chicago, saw a flickering shadow and was enamoured of it. He 
borrowed money on his little store and came back and bought that 
little motion picture theater. He then hired a little boy to play the 
piano and do the "tinkling" before and after the picture. As he sat 
and sold and took tickets most of the time, he watched the effect of the 
music on the audience this is a true incident. After one show, he 
suggested to the boy at the piano: "At the next show 'tinkle' the 
piano during the picture and see what happens." The boy did so, 
and that was the first time that music accompanied a picture. That 
merchant was Carl Laemmle and the little boy was Sam Katz. 

My appreciation of the moment is known to you all; my func- 
tion is to present these gentlemen who are here to join with me in this 
appreciation. The first one is not only a ranking officer in a com- 
pany, but is in charge of all its product; he has the soul and vision of 
an artist, and his great achievement has been to lead the way in 
raising the standard of our motion pictures Mr. J. Lasky, Vice- 
President of Paramount. 

MR. LASKY: Mr. President, Ladies, and Gentlemen: When I 
was a small boy I had several ambitions: first, to be a fireman ; second, 
to be a soldier; third, to be a sailor; and the other, to be an engineer; 
but until now I have never attained the ambition of being an engineer. 
After hearing the remarks of your President, however, I find I am 
an engineer. Just imagine wishing for something you had all the 


time and didn't know it! I want to come into the Society as a 
member so that I may have that distinction. 

It is a great source of comfort to the producers to know that the 
Society is existing and how vast is the great work you are doing. 
However, let me confess once more. One of my greatest worries 
was the coming of sound into the movies. I didn't believe in it and 
thought it would never arrive. I used to say it couldn't be done, and 
used a thousand arguments that now seem ridiculous. Every night 
we were faced with a problem I shall never forget, of turning ourselves 
inside out to adapt ourselves to this medium. The best thing seemed 
to be to retire; I am ashamed to say so now, but my first impulse 
was to quit. Thanks to the engineers and the gentlemen who give 
their lives to research and to science and all that it means, we poor 
humble followers did catch on and thank God for the sound and all 
that it means, and this time I don't care what you see in the future, 
I am for it and if I am alive I won't quit! 

MR. HAYS: I have repeatedly said that no story on the screen 
is half as interesting as the screen itself; it is particularly true of 
sound pictures. At the meeting which President Hoover held in 
Washington last winter, he said that nothing had happened in in- 
dustry more remarkable than how motion pictures had changed in a 
year and a half in almost a step. It is marvelous how industry 
adapted itself to it. 

The next introduction how we made from an admiral, a great 
executive the shot that sounded around the world was a pin drop 
compared to the development of sound on the screen, and most 
potent in that was Mr. J. E. Otterson, President of the Electrical 
Research Products, Inc. 

MR. OTTERSON: Mr. Chairman, Ladies, and Gentlemen: In 
my short connection with the motion picture industry, I have been 
less concerned with the "tinkling" that went on in motion pictures 
twenty -five years ago and more concerned with the "tinkering" that 
is going on now. It is necessary for the artistic effect of motion pic- 
tures that the process by which the result has been attained should 
be concealed. Due to this fact, I would say that the work of the 
engineer, as well as the motion picture industry of the future, lies in 
concealing the fact that an engineer has anything to do with motion 
pictures to bring about such a natural effect that the public will 
not associate with it any mechanical or engineering process. 

Feb., 1931] BANQUET SPEECHES 235 

MR. HAYS: The next presentation is the President of the Amkino 
Corporation of America, Mr. L. I. Monosson. 

MR. MONOSSON: It gives me great pleasure to say a few words 
about the relation of the Soviet cinematography to the American 
motion picture industry. Of course, our technical achievements at 
the present time are very small, but the American industry is thirty 
years old and the Soviet is only ten or twelve years old even less. 
We are very young, and this may be the reason why our achieve- 
ments are so small. For this reason we look to the motion picture 
engineers in America for help. Technical language is the same 
all over the world, and this may be the reason why the first contact 
with the Russian motion picture industry was made through the 
American Society of Motion Picture Engineers. 

MR. HAYS: The next presentation Mr. George E. Quigley, 
Vice-President of the Vitaphone Corporation. 

MR. QUIGLEY: I am a little fearful that I talk like a Vitaphone. 
I shall content myself with an expression of the pleasure I have of 
being with you. 

MR. HAYS: The next presentation is Mr. H. G. Knox, Vice-Presi- 
dent of the Electrical Research Products, Inc. 

MR. KNOX: As an engineer, I suppose I am in order in saying 
that the technical developments in the next year will be more start- 
ling than in the past. The work of Electrical Research Products is 
coordinated, and we are working in the closest possible way with 
the producer. We expect, with regard to the part that sound 
plays in motion pictures, that in the next two years we will have 
relative perfection. That will be accomplished with no more com- 
plicated apparatus, and the producer and the audience will get the 
benefit of this improvement in sound quality. 

The only message I have tonight is to assure the members of the 
Society of our willing assistance in help to solve the problems of 
sound pictures. 

MR. HAYS: The next introduction is the Vice-President of RKO, 
Major L. E. Thompson. 

MAJOR THOMPSON: I am as much out of place in this gathering 
as a cat in a strange garret, because I happen to be the only member 


of the Theatre Operating Commission. This seems to be a case of 
the engineer and the producer out to do the theater. I have heard 
a lot about the "tinkling" it was fine, it was cheap, and as the 
tinkling developed we got sound, but we got a bill with it. Out in 
front of every theater there is a little coop, sometimes with a girl 
in it ; but everybody is doing the same thing selling tickets and it 
is this that keeps the producers and the Society in business. 

I just want to leave one thought with you that in all this re- 
search work that you are going to do, I hope you do a lot and that it 
brings forth benefits for the theater; but when you do it, try and figure 
some way of keeping the expense down because the box-office is on 
its last legs. 

MR. HAYS: The next presentation is Mr. Paul Gulick, publicity 
director of Universal. 

MR. GULICK: Personally, I am very glad to meet face to face the 
gentlemen who caused the revolution in the motion picture business. 
You don't look revolutionary to me; you are able spokesmen and 
leaders; you have talked rationally and seem to formulate plans 
which will be helpful. 

My business is that of press agent, and it is my business to 
make people like the pictures and pay at the box-office that Mr. 
Thompson told you about. I have never had any ability to become 
an engineer. The only accomplishment I have attained is to get 
my name mentioned on the program tonight so that I can tell my 
wife where I have been. 

MR. HAYS: The next, my friends, is a very great artist and most 
distinguished international representative of this great business, 
Mr. Serge Eisenstein, the director who is here from Russia. 

MR. EISENSTEIN: Mr. President, Ladies, and Gentlemen: I 
don't like to make speeches. Please don't mind if my speech is 
bad; my feelings are not I am smiling. 

You know, everybody asks the employees if they like the boss, 
' 'Hollywood. ' ' The joke of that boss is that it will not smile. When 
you visit Hollywood you are shown the marvelous installations and 
the results of research, and at the end you are always invited to look 
at the pictures. The differences between the technical and artistic 
accomplishments are tremendous. I don't want to say that the 
pictures are not good, but behind the screen production, from the 

Feb., 1931] BANQUET SPEECHES 237 

artistic point of view you feel the lack of research such as is behind 
every engineering achievement. When I arrived in Hollywood I 
wanted to know: "Is there a university or high school of motion 
pictures?" And I received the answer: "No, there is not; the 
business developed so quickly but we can have everybody out- 
standing on Broadway for our business; we can have the best singers 
and artists so we don't need a university." Now, I think that is 
not the way to insure a really great development in art, and when we 
see such remarkable results on the technical side, it is because there 
is a scientific basis for them. I will say that you have some scientific 
organizations which work on this subject, such as Harvard and Yale. 
I had the honor of speaking in both places and saw what use is made 
of research there, but it is almost nothing. They are occupied with 
the theater drama, and I think that these universities, isolated as 
they are from the real motion picture business, can never provide 
the producers with the knowledge they must have. The only in- 
stitution which approaches what I have in mind is the Academy of 
Motion Picture Arts and Sciences. I want to say in leaving, that 
the greatest thing to be accomplished for the future of the motion 
picture business is the foundation of a high school or university for 
research on the artistic side. 

MR. HAYS: The next and last: A recent graduate of the Univer- 
sity of Southern California, who has come to New York on a visit, 
who is incidentally the star in a very great new picture which I have 
thought enough of to see twice in the projection room, whose shooting 
is as straight as his love is charming Mr. John Wayne. 

MR. WAYNE: I want you all to know that I consider it a very 
great honor to be presented here to people who are creating and 
aiding in the adjustment of our industry. This occasion recalls 
to mind the words of my partner in the picture, The Big Trail. One 
day we were watching the movements of the wagons, horses, and 
cattle in the picture and he said, "We actors are like that; we are 
driven and shoved, we don't know where." It is you people who 
are giving us something to work with, and I hope everything is going 
to be "ok" with sound. 

MR. HAYS: Mr. President, I have finished the task of introducing 
these gentlemen as you requested, and I close as I began: I give 
you these lines in all earnestness: For those who take the helm of 
leadership there is no stopping on the road of scientific and technical 



progress. One makes way for another. A true art form is a living, 
growing thing. You have learned to trust the courage and willing- 
ness of the industry and to go ahead; the industry, in turn, has 
learned to look to you with confidence for new and greater inventive 
progress. To your work, and to the work of those who make the 
pictures with the scientific wonders you provide, the American 
public and the world public has given an endorsement unparalleled 
in history. Such endorsement must keep us alert and alive to our 
great public responsibilities. 

PRESIDENT CRABTREE: After hearing all these eulogies, we realize 
more than ever our great responsibilities. Knowing that the eyes 
of the producers are focused upon us, we shall go back to our labo- 
ratories and workshops better prepared for greater accomplishments. 



In a previous report the theoretical aspects of good illumination 
in theaters were discussed. These included visual acuity and com- 
fortable vision. The former is improved by higher screen bright- 
ness and lower auditorium and screen illumination levels, and the 
latter by low contrasts between the picture and its surroundings and 
a higher order of room brightness. Since the committee's previous 
report, brightness and illumination tests have been made in a group 
of theaters especially selected for poor and good lighting conditions, 
for the purpose of combining visual observations with measurements, 
so that such measurements could later be interpreted for the benefit 
of theater managements, architects, and others. A test procedure 
was drawn up, covering the essential points reported on previously 
and other considerations developed later by the committee. Briefly 
the survey program covered the following points: 

1. An estimated quality of the projected picture by a number of 
observers with especial reference to visual acuity and comfortable 
viewing over an appreciable period of time. 

2. Brightness and illumination measurements of the screen, its 
surroundings, and various parts of the auditorium, noting the place- 
ment of light sources and their effect on visibility of the picture. 

About thirty theaters were given a preliminary survey and of these 
seven were given a thorough study. An analysis of the data obtained 
shows that with the screen brightness ranging from 2.5 to 10 milli- 
lamberts, there is no evidence of discomfort due to too great con- 
trasts, even in houses almost totally dark. Brightness below about 
3.0 millilamberts was unsatisfactory due to the reduction of visual 
acuity. In one theater having a screen brightness of about 9 milli- 
lamberts an impression of too high illumination was obtained. This 
seemed reasonable on account of the smallness of the house 800 
seats capacity. In the other 800-seat houses, in which visual acuity 
was satisfactory, the screen brightness was only about 3 millilamberts. 

* Presented at the Fall 1930 Meeting, New York, N. Y, 


In none of the theaters was there sufficient stray light to appre- 
ciably affect the picture. Measured values were less than 0.01 milli- 
lamberts, and in none of the seven were the contrasts in the picture 
too great. While black velvet was used to surround the screen in 
some of the theaters where good visual comfort was obtained, these 
houses were relatively narrow ; where gold, yellow, or similar hangings 
were employed, with higher brightnesses of about 0.05 millilamberts, 
the conditions were quite comfortable. 

In this connection it is interesting to note that it is common prac- 
tice to "screen" the pictures at the producers' studios with relatively 
high screen brightness and short observation distances, and to 
judge the contrasts and densities of the printed film by observa- 
tions made in this manner. Such conditions do not represent those 
obtaining in the theater, and more comfortable lighting conditions, 
comparable with those encountered in the field, should be established 
in the screening rooms. 

When theaters operate on the two-performance-a-day schedule, 
and people do not enter and leave during the performance, auditori- 
ums almost totally dark have commendable visibility characteris- 
tics. For the houses running continuous performances, intensity 
values of about 0.1 foot-candle were found satisfactory for taking 
seats easily, provided the eyes had gradually accommodated them- 
selves to that intensity in passing from the high intensities 
existing at the entrances. One of the most outstanding criticisms 
of nearly all the houses examined was the relatively high intensities 
in the lobbies compared with the values inside the auditorium. The 
intensities encountered, varying from 6 to 20 foot-candles to daylight 
values, should be somewhat lower to prepare the eyes for intensities 
of 0.5 to 2 foot-candles at the entrances of the auditorium. 

It is probably desirable that patrons find their seats without the 
aid of ushers' flashlights, so that, bearing in mind, the fact that the 
entrance and foyer intensities may be as high as 20 foot-candles or 
more, the gradation from 20 millilamberts to the very low values 
suitable for auditoriums requires carefully graded illumination in- 
tensities for the intermediate points. 

The .Screen Illumination Committee of the Academy of Motion 
Picture Arts and Sciences requested this committee to submit recom- 
mendations for screen illumination tests and a detailed description 
of the procedure outlined above was furnished to the Academy group 
for use in their work. 

Feb., 1931] 




Average foot-candles on 

screen 2 
Average millilamberts 

Stray light on screen 

Brightness of screen 

surroundings ML. 
Brightness on front 

wall ML. 
Foot-candles, front row 

Foot-candles, middle 

row center 
Foot-candles, back row 

Foot candles, center 

Maximum light source 

brightness in field of 

vision ML. 



















0.0025 0.0027 0.0050 

(?) 0.054 0.0064 

0.003 0.017 0.009 

0.17 0.16 0.33 

0.012 0.35 0.51 

0.016 0.25 0.37 

6.0 7.3 





Daylight intensities 

2280 4 35.3 
Observed visual com- Comfort- Uncom- Comfort- 
fort able fortable able 
Visual acuity Very Fair to Fair to 

good good very good 

5 No film in projector. 
Wide film. 
4 Bare lamp, visible only from upper balcony. 

0.04 0.05 

Comfort- Comfort- Very corn- 
able able fortable 
Poor Good Good Good 

The committee has found this quite an extensive undertaking. Al- 
though progress has been slow we believe it will ultimately furnish 
a fund of information of great value to non- technical as well as 
technical workers. 


C. E. EGELER, Chairman 


MR. FRIEBUS: In discussing the illumination necessary to permit patrons to 
pass into and out of the theater during the performance, the matter of the color 
to be used for lighting and the minimum amount required was neglected. I 
suggest that it be considered. I believe that the contraction of the pupil is 
greater for the same intensity of illumination at the red end of the spectrum than 
at the blue. Perhaps better illumination could be obtained with blue light, which 
affects the eye less in viewing the screen than if red light were used. 


MR. FARNHAM: In our survey, we found that theater owners are quite prone 
to use red in winter to suggest warmth, and blue or green in summer to suggest 
the idea of coolness. This is a feature with which the committee has had to con- 

PRESIDENT CRABTREE: I believe that in many cases the level of illumination 
in the theater is too high for comfortable vision, so that it is difficult to concen- 
trate on the picture. To me, the picture becomes more real the darker the sur- 
rounding parts of the theater. Of course, it is admitted that absolutely dark 
theaters are out of the question nowadays. There is no doubt, however, that in 
the future, the dark condition must be approached more and more. 



The membership of our Society has continued to grow until we now 
have 756 active, associate, honorary, and sustaining members. There 
have been very few losses through delinquency or otherwise during 
the year. Sixty-two members were reported as delinquent, of 
which number this committee succeeded in holding in the Society 
all but twelve, while practically all of those who dropped out did 
so because they left the industry. 

Your committee has tried to bring the Society to the attention of all 
technicians in the motion picture industry. It has been a booster 
committee, having members in all large cities and foreign coun- 
tries where motion pictures are produced. Once each year the commit- 
tee invites all members of the Society to recommend those whom 
they know to be eligible for membership. Occasionally, applications 
have been held up for some time by the Board of Governors pending an 
investigation of the classification of the applicant; this delay is 
generally caused by the diffidence of the applicant to record his own 
accomplishments and qualifications on the application form. 

The relatively high entrance fee and annual dues charged by the 
S. M. P. E., as compared with other similar organizations, prevents 
many of the younger technicians from applying for membership. The 
committee, after considerable deliberation, unanimously recom- 
mends that the entrance fee and dues be reduced at the earliest 
date consistent with our ability to maintain the high standard of the 
JOURNAL and semi-annual meetings of the Society. 

This committee has made a special effort to secure subscriptions 
for the JOURNAL. Nearly 200 subscribers have been added to the 

* Presented at the Fall 1930 Meeting, New York, N. Y. 

Feb., 1931] 



circulation this year and we might well expect an equal increase for 
the coming year with equal effort. With 800 subscribers the JOUR- 
NAL could be made self-supporting. 

In conclusion, your committee requests continued effort on the 
part of all members in assisting the committee in its work of increasing 
the membership of the Society and the list of subscribers to the 




H. T. COWLING, Chairman 






The Papers Committee is planning a papers program of unusual 
interest for the Spring Convention in Hollywood and is arranging this 
program with unusual care, so that members attending the convention 
will secure maximum value from the papers sessions. In working 
toward this end, several changes in the procedure for handling con- 
tributed, papers have been made, and members planning to submit 
papers for presentation are asked to note these changes carefully. 
The committee earnestly requests the cooperation of all members to 
enable it to carry out its plans effectively. 

(1) The new plan requires that all manuscripts of papers for the 
Convention be submitted by April 1st. The dates for the Convention 
are May 25th to 28th, inclusive. This will allow a period of one month 
for review of papers by members of the committee and by special 
experts within the Society. The necessity for such careful review is 
obvious if a uniform standard is to hold for all papers accepted. 

(2) It is also planned, during the interval after April 1st, as a 
special feature of the next Convention, to prepare rather full abstracts 
of papers and to distribute preprints of the abstracts to members at 
the Convention. This will permit those attending the Convention 
to know the general character of papers before they are presented, so 


that they may not miss sessions in which papers of particular interest 
to them are offered. It is also expected that these extended ab- 
stracts will stimulate discussion of papers presented and thus make 
the sessions more interesting and instructive. 

(3) Each prospective author is asked to submit, in addition to his 
manuscript, (a) a short abstract of about 100 words summarizing his 
paper, which can be used for program purposes and for press releases, 
and (b) a short biographical sketch (see page 259, this issue of JOURNAL) 
for JOURNAL publication. Since the program and the press releases 
are the usual means by which members and guests obtain a detailed list 
of papers, authors will help to insure a full audience for their papers 
by providing the short abstract requested. 

(4) All manuscripts should be sent to the Editor of the JOURNAL, 
Sylvan Harris, 33 West 42nd Street, New York City. Each manu- 
script should be accompanied by such diagrams and photographs as 
are proposed to be included in it. Detailed instructions to authors 
are contained in a pamphlet entitled, "Instructions to Authors" which 
may be obtained upon application to the Editor. 

The committee is anxious to obtain a well-rounded program, and 
requests that all prospective authors send the titles of their proposed 
papers to the Editor as early as possible. If titles and authors of 
prospective papers can be obtained in this manner it will assist the 
committee in planning. 

The committee believes that members will agree that the features 
of the new plan as outlined are desirable and will do their utmost to 
cooperate with the committee. 

O. M. GLUNT, Chairman 


The principal work of the Progress Committee for many years 
has been the compilation of data giving the results of scientific ex- 
perimentation, descriptions of new apparatus, and the discussion 
of practices in the industry. This information has been obtained 
from the trade, from technical journals published in various parts of 
the world, and from personal reports by committee members. A 
general report, summarizing the collected data, is presented at each 
of the semi-annual meetings of the Society. Later, this information 
is published in the Society's JOURNAL, thus making it accessible for 
all members and others receiving the JOURNAL. 


The files of the committee contain much useful information which 
may be consulted at any -time by writing the chairman. It seems 
as if more use should be made of this information, which has been 
compiled at considerable personal expense by the members of the 


As to the semi-annual report, the present chairman has made a 
conscientious effort to arrange the report in the most useful way 
possible for easy reading. There are eight general divisions as 
follows: (1) Production, (2) Distribution, (3) Exhibition, (4) Ap- 
plications of Motion Pictures, (5) Color Photography, (6) Amateur 
Cinematography, (7) Statistics, (8) Publications and New Books. 
A comprehensive bibliography of references is also included. It is 
thought that this arrangement is a logical one. Few people ever 
read all of the material in a progress report but almost everyone 
is interested in certain sections of the report. 

There may be other ways of arranging the material, however, 
which will make it more accessible. It may be considered by some 
members that one of the semi-annual reports ought to be shorter, 
giving only a generalized rather than a specific survey. The chair- 
man has worked on the basis that a progress review should be current, 
and should contain enough detailed information about most of the 
items to acquaint the reader with the essential facts about each sub- 

It is the aim of your committee to make this report the most 
accurate and complete review of conditions in the industry published 
in the world. Any suggestions which you may have toward this 
end will be appreciated. 



The Committee on Studio Lighting is preparing a questionnaire for 
submission to studios throughout the world, so as to be able to formu- 
late a comprehensive report as to what is being done throughout the 
entire industry. The committee would be very glad to receive 
suggestions from any member on the questionnaire or on any subject 
related to Studio Lighting. Please address M. W. Palmer, in care 
of the New York Office of the Society. 

M. W. PALMER, Chairman 


The following abstracts are published by courtesy of the Eastman Kodak Company, 
publishers of the Monthly Abstract Bulletin of the Kodak Research Laboratories. 

Variation of the Brilliance of Distant Objects with Distance. M. HUGON. 
Sci. Ind. Phot., 1, May, 1930, p. 161. A mathematical study of the variation of 
the brilliance of distant objects with the distance has been made, considering 
atmospheric absorption and light scattering. The wave-length used in viewing 
the objects must be chosen, considering the relative values of absorption and 
scattering. The results are employed in connection with some photometric 
studies using wedge and photography. Using niters, it was found that the ratio 
of direct sunlight to diffused light from the sky is practically constant when the 
sun is 30 degrees above the horizon. Contrast is found to increase with the wave- 
length. The experimental results are closely in agreement with theory. As an 
application, photographs have been taken of distant objects using panchromatic 
and infra-red sensitive plates and suitable filters. 

Deterioration of Sulfite Hydroquinone Solutions and the Mode of Activity 
of Old Solutions. J. PINNOW. Z. Wiss. Phot., 27, No. 11-12, 1930, p. 344. By 
careful oxidation with permanganate in sulfuric acid solution in the cold, a- and 
/3-hydroquinone disulfonic acid gave compounds which liberate, by boiling, oxalic 
acid and large amounts of sulfurous acid. A similar oxidation by air could explain 
the formation of the complex compound observed by Schilow and Fedotoff, which 
is formed in solutions having no more developing power. The sulfite solution in 
the developer is better protected against oxidation by a mixture of a- and 
/3- hydroquinone disulfonate than by hydroquinone.' 

Receiving the Image. D. L. WEST. Mov. Pict. Rev. Theater Management, 25, 
September, 1930, p. 8. Details of television images as received have improved 
markedly since 1926. A type of home receiver is briefly described. Synchroniza- 
tion in these sets is accomplished by utilizing one of the main component fre- 
quencies in the received television image current to drive a small synchronous 
motor coupled directly to the shaft of the scanning disk motor. For a showing at 
the London Coliseum, in July, 1930, a large multi-lamp screen was used consisting 
of a bank of small electric lamps. Each lamp was connected to a commutator 
device. A ground glass screen was placed in front of the lamp bank. 

F/2.5 Leica Camera. Amat. Phot., 70, Oct. 15, 1930, p. 375. A new model of 
the Leitz "Leica" has an//2.5 lens, and takes interchangeable lenses, one an//3.5 
lens of 35 mm. focus and the other an//4.5 lens of 135 mm. focus. 

Small Film Pictures. J. J. HANSMA. Focus, 17, Aug. 30, 1930, p. 468. Equip- 
ment and technic for developing and printing small negatives, such as "stills," 
made on motion picture film. The following negative developer formula is recom- 
mended: (a) Oxalic acid, 0.4 gm.; metol, 4.0 gm.; pyrogallol, 12.0 gm.; 
potassium metabisulfite, 1.0 gm., and water to 200 cc. (b) Sodium sulfite 


(crys.), 48 gm.; water to 168 cc. (c) Acetone, 40 cc.; water to 200 cc. For 
use, 15 parts of each of the three solutions are diluted with 80 parts of water. 

Tanar Corporation Introduces New Sound Truck. Amer. Cinemat., 11, 
September, 1930, p. 15. The first Roos portable recorder used the single film 
system, and the apparatus, weighing 70 pounds, could be packed into two cases. 
The second portable outfit is fitted into a Dodge speed truck which is insulated to 
serve as a monitor room. A flashing lamp is used and amplification is sufficient 
for four microphones and six cameras. Power is obtained from storage batteries 
which can be charged from the truck motor in the field. 

Air Column Speaker. Amer. Projectionist, 8, August, 1930, p. 11. The new 
unit uses the amplifying system feeding a magnetic or dynamic speaker in the 
usual way. The speaker has a vibrating reed which is actuated by the amplified 
signals from a radio set or phonograph and it in turn acts on a sensitive air valve, 
causing it to open and close in accordance with the frequency of the sound being 
produced. The opening of the air valve allows a minute jet of air under twenty 
pounds pressure to escape, the sequence of these jets forming a musical note which 
is amplified by resonance in the exponential horn. Laboratory tests show that the 
air valve responds to frequencies quite uniformly from 30 to 14,000 cycles. It is 
pointed out that the great volume obtained by the speaker is not caused by the 
blast of air but only by the escape of air through the minute air valve. 

Triergon Process for Making Phonograph Records by the Use of Sound Films. 
H. VOGT. Kinotechnik, 12, July 20, 1930, p. 385. A sound record of the variable 
density type is made on film. This is reproduced on a wax record by means of 
a lamp, light-sensitive cell, amplifiers, and electromagnetic stylus. For the best 
reproduction, it is stated to be necessary to make the reproduction at one-fortieth 
the speed at which the original record was made. In this way, the effect of the 
natural frequency of the armature of the electromagnetic stylus is said to be 

Transmitting Images. D. L. WEST. Mm. Pict. Rev. Theater Management, 
25, August, 1930, p. 12. Visible light sources commonly used for subject scan- 
ning have been replaced by a scanning source composed of invisible radiation, 
which is claimed to make the physical conditions more pleasant for the subject 
being "televised." With present scanning equipment it is possible to accom- 
modate several at a time, although, unless the size of the light spot is reduced in 
proportion to the increase in area scanned, detail is obviously lost. The article 
includes illustrations of equipment used as well as views of the transmitting 

Eberhard Effect and Its Significance for Photographic Photometry. N. VAL- 
ENKOV. Z. Wiss. Phot., 27, No. 8-9, 1930 p. 236. The Eberhard effect is in a 
high degree dependent upon the sharpness of the photographic picture. For the 
straight line portion of the H. & D. curve the effect is proportional to the differ- 
ence of the densities between the pictured object and the surrounding field. If 
the surface of the object is large the Eberhard effect shows an edge effect which is 
never wider than 1.5 mm. Pictures smaller than 3 mm. in diameter show in- 
creased densities through the Eberhard effect. The effect is independent of the 
form of the picture. Very fine grain photographic emulsions show no Eberhard 
effect. With increasing average grain size the effect increases. For x-rays there 
is almost no effect. The increase of density caused by the Eberhard effect is in 

248 ABSTRACTS [J. S. M. P. E. 

all cases very small. Development with metol-hydroquinone and potassium 
bromide did not show any more effect than development with ferrous oxalate 
developer. The effect is independent of the intensity of the light source. The 
effect has little significance for both astrophotometry and spectrophotometry. 
With x-rays especially, it has no significance at all. 

Peko Camera on the Way. Movie Makers, 5, September, 1930, p. 476. This 
amateur standard spring driven camera is of the vertical type, having one reel 
located above the other inside a cast metal case. Features are : a self-contained 
footage meter; a finder adapted for either waist or eye level exposures; and a non- 
buckling film guide. The spring release button is located on the front of the 

Wide Film Cinematography. A. EDESON. Amer. Cinemat., 11, September, 
1930, p. 8. More than half a million feet of film was used in photographing 
The Big Trail. No trouble was encountered from abrasion, but film buckle, 
leading to the destruction of several camera motor drives, was experienced when 
the film spools were not carefully smoothed before insertion in the magazines. It 
was found necessary to use lenses of exactly double the focal length of those 
employed for 35 mm. shots. The photographic quality in the large film is 
claimed to be greatly superior. 

European Sound Picture Industry. Electronics, 1, September, 1930, p. 282. 
An outline is given of interrelations of the various sound picture interests dealing 
with the relationships brought about by capital and patent pools and technical 

Walturdaw's Projector Range. Kinemat. Weekly (Design and Equipment 
Supp.~), 164, Oct. 9, 1930, p. 41. Notes are given on the Hahn II, the Ernemann 
II, and the Ernemann III projectors. All are fitted with a fire prevention device. 
Should the film break above the intermittent sprocket, the top loop naturally 
enlarges, lifts a flap, actuates a mercury switch, and cuts off the light beam and 
motor current. The Ernemann III projector has a lens mount capable of carry- 
ing lenses of 80 and 100 mm. diameter, thus enabling an aperture of //1. 9 to be 
used on lenses of almost any focal length. By replacement of the standard gate, 
this model can be rapidly adapted for wide film; the exact width is not specified. 

Theory of the Motion Picture Claw Pulldown Mechanism. C. FORCH. Kino- 
technik, 12, Aug. 5, 1930, p. 407. A mathematical analysis is made of several 
claw, pull-down movements. It is concluded that, with the usual claw pull-down 
mechanisms, conditions can be arranged to obtain a movement that very closely 
approximates that obtained with a Geneva pull-down. If a radially slotted disk 
is mounted on the end of the pull-down crank shaft so as to be driven by the pin 
of a crank with its shaft parallel but eccentric to the pull-down crank shaft, the 
pull-down can be effected in 90 degrees or less, instead of 180 degrees. With a 
Geneva pull-down, the steadiness of the picture depends upon the absolute identity 
of the four members of the Maltese cross. With the claw pull-down, each stroke 
is made with the same member, and a source of unsteadiness is thus removed. 

An A spheric Mirror of High Efficiency for Motion Picture Projectors. F. 
HAUSER. Kinotechnik, 12, July 20, 1930, p. 379. A mirror for motion picture 
projectors is said to combine the advantages of the spherical and the elliptical 
mirrors. It is built up from several zones in such a manner as to have a small 
amount of spherical aberration. The mirror is said not to be as sensitive to the 

Feb., 1931 J ABSTRACTS 249 

longitudinal adjustment of the arc as the elliptical mirror, but to be highly efficient. 

Subjective Density Measurements. P. LOB. Kinotechnik, 12, Aug. 20, 1930, 
p. 435. In the instruments for measuring densities subjectively, two parts of a 
photometric field are matched visually. The optical systems of a number of 
different types of photometers are described, and the advantages and disadvan- 
tages pointed out. Some of the precautions necessary for the different types are 
given. The polarization photometer has the disadvantage of requiring a mono- 
chromatic light. With the wedge type of photometer, the wedge should be of the 
same material as the object whose density is to be measured, and it is advisable 
to increase the intensity of the light with increase in the density to be measured, 
so that a beam of moderate brightness will always enter the eye. In diaphragm 
photometers, the diaphragm must be exactly in the plane of an optical pupil. 
Sector photometers have the advantage that no lenses are required. The Callier 
effect must always be avoided. Instruments in which the conditions are identical 
in the two optical paths automatically eliminate this source of error. 

Lagorio's Color Table. L. KUTZLEB. Kinotechnik, 12, July 20, 1930, p. 383. 
A color chart is made of a number of narrow vertical color strips of different 
spectral hue and known saturation alternating with neutral strips, each having a 
number of steps of different reflecting power from top to bottom. The spectral 
brightness curve, as rendered by any plate or film may, it is claimed, be obtained 
by photographing the chart and tracing a line through the points where the im- 
ages of the color strips match the images of the adjacent neutral strips. The 
ideal visual brightness curve is printed on the chart, so that the rendering of any 
plate may be compared with it. The chart is intended for testing panchromatic 
plates and films and for determing proper correcting filters. 

Wide Film versus Wide Image on Standard Film. J. J. FINN. Mot. Pict. Pro- 
jectionist, 3, August, 1930, p. 31. A number of producers and exhibitors oppose 
the adoption of Grandeur 70 mm. film or any other wide film by the motion picture 
industry, because it would necessitate the installation and operation of entirely 
new equipment. They favor a process which will give a satisfactory wide film 
image with slightly modified standard reproducing equipment. In the Fear process, 
using a wide image on standard film, the film is run horizontally in the camera and 
the projector. By this method pictures of proper proportionate height and width 
are possible. A system has been proposed in which the picture is taken on 70 mm. 
film and is subsequently reduced in the printing operation on 35 mm. film. A special 
three-combination lens of extremely short focal length is used in reproduction. 
High intensity lamps drawing 160 amperes are employed for illumination. Some 
blank space is left between the film frames, which is dealt with in projection by a 
masking arrangement. Many printing difficulties and optical problems are 
encountered in the new system. Loss of definition in printing from 70 mm. to 
35 mm. and the great magnification required to secure a screen image of 45 feet 
are problems confronting the proponents of this process. 

250 ABSTRACTS [j. S. M. P. E. 


1,775,938. I. KITSEE AND D. C. LAW, assigned to Cinema Laboratories Corp. 
A method of coloring the uncovered surface of a motion picture film which is pro- 
vided with a photographically developed emulsion disposed over the surface in 
transparent colored relief figurations with minute interstices therebetween. The 
method consists in moving the film through a substantial vacuum and simultane- 
ously applying to said film, while the air in said interstices is substantially ex- 
hausted, a liquid coloring material dissolved in a solvent of celluloid in whiclj the 
emulsion is not soluble, the color of said liquid being complementary to that of the 

1,776,969. E. H. FOLEY, assigned to Sound Films Corporation. An apparatus 
for simultaneously photographing scenes on a negative film and recording the 
sounds on a plurality of films on which positive prints are to be made. This com- 
prises feed devices for moving both positive and negative films in synchronism, 
the positive films being moved continuously, and the negative film intermittently, 
and sound recording devices engaging each positive film at a point adjacent to 
the picture areas thereof. 

1,777,257. A. L. V. C. DEBRIE. A photographic objective mount, permitting 
focusing without rotating the objective, including a sleeve member carrying the 
lenses and having a grooved cam on one side thereof, which is engaged by a pin 
supported by a lever fastened to the apparatus. Upon swinging the lever, the 
sleeve member is moved in or out of its casing. The cam is designed according 
to the focal length of the objective. 

1,777,418. H. W. ROGERS. Motion picture and sound apparatus, having two 
turntables driven by a motor, are synchronized by a controlling means comprising 
two pairs of film controlled switches, a stationary and a power driven rotary elec- 
tromagnet for each turntable, a flexible magnetic disk disposed between the elec- 
tromagnets and connected to its turntable to control the movement of the same, 
a circuit including a source of energy and its electromagnet and switch, and means 
connected in each circuit for the control of the other switch of the pair, whereby 
the closing of one switch and its electromagnet will de-energize the other electro- 

1,778,104. W. J. CONKIE, assigned to Alexander Industries, Inc. A method of 
synchronizing the words and music of a sing film comprising the uniform pro- 
jection of time indications, bearing a definite relation to the number of frames pro- 
jected, during the playing of the song. 

1,778,139. R. JOHN. A color motion picture film of the dye transfer type, 
having an image comprising minute color dots grouped to represent a natural 
photographic record of lights and shades, said dots containing substantially the 
same quantity of imbibed dye per unit of surface for the various colors used. 
This film presents an unbroken image at above 50 diameters enlargement. 

1,778,351. L. W. BOWEN, assigned to Spiro Film Corporation. Motion pic- 
ture apparatus using a disk film which is rotatably mounted on a carriage having 
a rectilinear movement in a plane at right angles with the objective. The driving 
mechanism is operated in one direction only and automatically returns the car- 
riage to its original position after a complete film has been projected, whereby a 
film may be repeatedly projected. 

Feb., 1931] ABSTRACTS 251 

1,779,947. A. S. NEWMAN. Motion picture printing apparatus having a 
printing sprocket, the teeth of which are separated by a circumferential distance 
equal to the spacing of the pictures, the teeth on one side being slightly shiftable 
with respect to the teeth on the other to accommodate irregularities in the film. 
Two auxiliary sprockets are resiliently mounted on their shafts to keep the film 
taut over the printing sprocket, feed and take-up sprockets, and gearing whereby 
all of the sprockets are driven. 

1,780,025. E. MARKENBERG, assigned to Agfa Ansco Corporation. A process 
of developing films by reversal, comprising subjecting the film to an underdevelop- 
ment, dissolving the silver image, developing the remaining silver salt image after 
a second exposure, and then equalizing the excessive density of the reversed image 
by means of a solvent for silver having the character of uniform reducing action. 

1,780,039. I. PECHAN, assigned to The Czechoslovak Co. A tripod adapted 
to facilitate the leveling of a camera having eccentrics engaging bearings in the 
head and shafts therefor supported by the feet. 

1,780,123. N. FLORINE. A continuous-feed motion picture projector in which 
optical compensation is effected by lenses moving in a rectilinear track in front 
of the projection aperture. These lenses are resiliently mounted in radial 
grooves provided in a rotary disk. 

1,780,225. E. DE MOULIN. A two camera tripod head having an inverted 
L piece to support one camera in inverted position to facilitate the taking of trick 

1,780,311. A. PAPO AND A. GENTILINI. A continuous-feed motion picture 
projector, in which the film is pulled through the apparatus by the take-up reel, 
having a reciprocating optical system with a portion of its axis parallel to the 
plane of the film, and including a reflector which is moved by a film engaging mem- 

1,780,384. I. I. GREEN. A filter holder, adapted to be clamped to the lens 
mount, provided with a hinged top to facilitate the insertion of one or more filters 
in a frame and resiliently retained in position. 

1,780,510. A. G. WISE, assigned to Metro-Goldwyn-Mayer Corp. A film reel 
comprising a flange, and a hub having means for decreasing its normal diameter to 
facilitate the removal of the film upon being wound. 

1,780,585. A. FRIED, assigned to William Fox Vaudeville Co. A tripod head, 
mounted for rotation about a vertical axis, having an adapter for rotation about a 
horizontal axis and a means including a gear train and flywheel to steady the move- 
ment about either axis. 


Photography Its Principles and Practice. C. B. NEBLETTE. 2nd edition. 
D. Van Nostrand Co., New York, N. Y., 1930, 615 pp., $6.50. The original 
1926 edition has been a useful textbook for the beginner and even more advanced 
students of photography. New material in the 1930 edition includes information 
on the modern theories of latent image formation, the theory of sensitivity of 
emulsions, the constitution of color sensitizing dyes, and the theory of develop- 
ment and fixation. The author appears to be unaware of the existence of the 
Transactions and JOURNAL of the Society of Motion Picture Engineers, and it is 
unfortunate that the extensive information on the theory and practice of pho- 
tography which they contain has been overlooked. 

The chapter on color photography is inadequate and could have been extended 
at the expense of some of the chapters dealing with little used processes. 

Any book for the student which deals with practice should dwell, if at all, on 
those applications which are of importance in every-day life. The most important 
applications of photography are to photomechanical methods and motion 
pictures, neither of which are mentioned. However, a perusal of the book and 
especially the chapters on sensitometry and the theory of development is recom- 
mended to all motion picture technicians. J. I. CRABTREE 

Introduction to Physical Optics. JOHN KELLOCK ROBERTSON. D. Van 
Nostrand Co., New York, N. Y., 1929, $4.00. Optics is unquestionably the 
most difficult branch of physics for the reason that there are no simple phenomena 
with which the student may begin his study of the subject. He must begin to 
study it all at once, so to speak, whereas in mechanics, for example, he may begin 
with statics and leave the more difficult concepts of dynamics until later. In this 
sense, any work on optics must of necessity be more in the style of a treatise 
than a textbook. It seems fair to say that the "Introduction to Physical Op- 
tics" by John K. Robertson is the closest approach to a textbook that the re- 
viewer has examined. The author has managed his material so skillfully that 
it seems to satisfy well the avowed purpose of the book, namely, to supply "the 
needs of two classes of students: (1) those who, at the outset of an intensive 
study of physics, are laying a thorough foundation for subsequent work in the 
theory of optics; (2) those specializing in other branches of science, for whom a 
general knowledge of modern views of light is desirable and, indeed, frequently 
indispensable. It is hoped, too, that the treatment is such that an appeal may 
be made to the general reader who desires to have some acquaintance with 
the fascinating problems of modern physics problems many of which are most 
directly approached through the study of light." 

The early chapters of the book deal with wave motion and the interpretation 
of the phenomena of reflection and refraction on this basis. This is followed by 
a short discussion of lenses and optical instruments. There are then six chapters 
dealing with the classical phenomena such as interference, diffraction, and polari- 


zation, which are followed by a discussion of the electromagnetic theory of light, 
the origin of spectra, the quantum theory, and radiation potentials. The volume 
ends with a discussion of the more recent attempts to fuse the two conflicting 
theories concerning the nature of light. 

The author has given particular attention to the clarity of presentation, which 
is assisted by a large number of excellent photographs and line drawings. A set 
of problems with answers is given at the end of each chapter. These are always 
useful for classroom instruction but perhaps even more for the technical man 
whose optics are a bit rusty and who desires to work up the subject by himself. 


Fabrikation und Prufung der photographischen Materialien (Manufacture and 
Testing of Photographic Materials). W. NAUCK AND E. LEHMANN. Union 
Deutsche Verlagsgesellschaft, Berlin, Germany, 1928, 274 pp., 68 illustrations. 
The first section of this book is intended for the beginner and contains little of 
interest to those engaged in manufacture It deals with the manufacture of 
photographic materials and contains the following chapters : 

(1) The Preparation of Sensitive Emulsions and Photographic Papers and 
Plates; (2) Photographic Raw Stock and Baryta Paper; (3) The Manufacture of 
Film Base; (4) Recovery of Solvents Used in Film Manufacture; (5) Coating 
Emulsions on Glass Plates; (6) Coating Emulsions on Paper; (7) The Coating of 
Emulsions on Films. 

The second section of the book, which deals with the testing of photographic 
materials, is of much greater value and is a creditable assemblage of the pub- 
lished information on the testing of gelatin and chemicals used in photographic 
manufacture, the analysis of film base materials, the testing of their physical 
properties, the analysis of emulsions, and the sensitometry of photographic ma- 
terials. J. I. CRABTREE 



J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 
Los Angeles, Calif. 

M. W. PALMER, Paramount Publix Corp., 35-11, 35th Ave., Long Island City, 

N. Y. 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

E. I. SPONABLB, 277 Park Ave., New York, N. Y. 





W. V. D. KELLEY, Chairman 










W. C. KUNZMANN, Chairman 

C. L. GREGORY, Chairman 



Membership and Subscription 
H. T. COWLING, Chairman 





O. M. GLUNT, Chairman 

D. McNicoL 


G. E. MATTHEWS, Chairman 

















[J. S. M. P. E. 







Projection Practice 

H. RUBIN, Chairman 


Projection Theory 
W. B. RAYTON, Chairman 


W. WHITMORE, Chairman 




H. B. SANTEE, Chairman 

Standards and Nomenclature 
A. C. HARDY, Chairman 



Studio Lighting 
M. W. PALMER, Chairman 











Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

D. MACKENZIE Chairman E. HUSE, Secretary 

L. E. CLARK, Treasurer 

Feb., 1931] 



Vice- President 















Chairman, Pacific 

Coast Section 



Chairman, New York 


Chairman, Chicago 



Conklin, O. E.: Massachusetts Institute of Technology, Physics, 1914; 
Assistant in Physics, 1915-16; Master of Science degree, 1917; Bausch & Lomb 
Optical Co., 1917-19; Physicist, Du Pont Co. and Du Pont-Pathe Film Co., 
1919 to date. Member of American Optical Society. 

Goldsmith, A. N.: B.S., College of City of New York, 1907; Doctor of Philoso- 
phy, Columbia University, 1911 ; Associate Professor of Electrical Engineering of 
College of City of New York (life appointment) ; Consulting Engineer of General 
Electric Company, 1915-17; Director of Research of Marconi Wireless Telegraph 
Company of America, 191719; Director of Research of Radio Corporation 
of America, 1919-22; Chief Broadcast Engineer of Radio Corporation of America, 
1922-27; Vice-President and General Engineer of Radio Corporation of America, 
1927 to date. 

Matthews, G. E.: Born August 22, 1897, at Ortonville, Minn. B.S., Uni- 
versity of Minnesota, 1920; M.S., University of Minnesota, 1921; Photographic 
chemist and technical editor, Research Lab., Eastman Kodak Co., July, 1921, to 
date. Member, American Chemical Society; Fellow, Royal Photographic So- 
ciety; Alpha Chi Sigma. 

Puller, George: Born July 2, 1888, New York, N. Y. B.S. in M.E., 1912; 
B.S. in E.E., Cooper Union, 1915; Post-Graduate M.E., 1916; designing en- 
gineer and partner, The Pull-Man Engineering Service, 1919-20; Apparatus 
Development Department, Bell Telephone Laboratories, Inc., 1920;. Radio 
Department, 1922; development of reproducing equipment for sound pictures, 
1926 to date. Instructor, Cooper Union, Dept. of Machine Design, 1920 to date. 
Associate member, American Society of Mechanical Engineers. 

Serge, Bobrovsky Igor: Born March 28, 1893 ; Tifflis Russia Military En- 
gineering School and Emperor Nicholas First, St. Petersburg, Russia, 1913; 
Officer Electors Technical School, St. Petersburg, Russia; Officer of Signal 
Corps of Russian Imperial Army, 1913-21; Union College, Schenectady, N. Y., 
1922 ; Radio Engineer, General Electric Company, Schenectady, 1923-26 ; United 
Reproducers Corporation, Rochester, N. Y., 1926-28; Chief Engineer of Valley 
Appliance, Inc., Rochester, N. Y., 1928-29; Member of Institute of Radio En- 

Taylor, John Bellamy: Born at Brookline, Mass. Graduated from Massa- 
chusetts Institute of Technology in E.E. ; with the General Electric Company, 
Engineering and Laboratory Divisions, 1919 to date. Member, American In- 
stitute of Electrical Engineers and American Association for Advancement of 


260 SOCIETY NOTES f J S. M. P. E. 


Meeting of the Board of Governors. At a meeting of the Board of 
Governors on December 19, 1930, at the Hotel Pennsylvania, New 
York, N. Y., a large amount of business was transacted, including the 

(1) It was resolved: "That an Open Forum be established in 
the JOURNAL, in which might be published letters and communications 
from members relating to material in the JOURNAL or other matters 
appertaining to the welfare of the Society, subject to the discretion of 
the Editor and Board of Editors. 

(2) Resolved that an acknowledgment of appreciation for the 
services rendered by Mr. L. A. Jones and his associates in editing 
the JOURNAL during the year 1930 be published in the pages of the 

(3) Numerous business matters relating to the London Section 
were discussed and in response to requests from the London Section 
for a refund of membership fees and special subscription rates to 
the JOURNAL, the following motions were made and passed: 

(a) Resolved that any London Section member may, at his request, be re- 
garded as terminating membership in the Society on December 31, 1930, and 
that his individual liability shall be satisfied by payment of all back dues and 
first quarter's dues for the term of 1930-31. 

(b) Resolved that the Board of Governors instruct the London Section to 
make an immediate accounting and forward to the General Treasurer of the 
Society all monies due the parent body. This accounting shall be made on the 
basis that those members who wish to withdraw from the parent body shall be 
refunded three-fourths of the current dues paid. 

(c) Resolved that the JOURNAL be supplied to British members at the standard 
price of $12.00 per annum with the concession that the heavy foreign postage be 
borne by the Society. 

The Spring Convention. At the meeting of the Board of Governors 
on December 19, 1930, it was resolved that the Spring Convention 
be held in Hollywood, Calif., May 25th-28th, inclusive. Mr. W. C. 
Kunzmann, chairman of the Convention Committee, has announced 
the selection of the Roosevelt Hotel as Society headquarters. 

Mr. O. M. Glunt, chairman of the Papers Committee, announces 
that the Papers Program will include a series of symposiums on (a) 
sound recording, (b) color, (c) film properties and processing methods, 
and (d) studio practice. 

An invitation to collaborate in the Spring Convention has been 

Feb., 1931] SOCIETY NOTES 261 

extended to the Academy of Motion Picture Arts and Sciences, 
Hollywood, Calif. 

Mr. C. L. Gregory, chairman of the Historical Committee, is 
arranging an exhibition of historical films and apparatus. 

The Wide Film Situation. The subcommittee of the Standards 
Committee, under the chairmanship of Mr. M. C. Batsel, has dis- 
cussed specifications for a wide film standard, and, having finally 
reached an agreement, the committee has arranged for the manu- 
facture of a quantity of the film. The General Theatres Equipment 
Corporation has agreed to construct the necessary projectors for 
testing out this film. If these tests are satisfactory, particulars 
regarding the new standard will be circulated to the membership 
for discussion and approval. 

The Aims and Accomplishments Booklet. This booklet, recently 
issued and circulated to all members, contains abstracts of all papers 
presented at the Society conventions together with a subject and 
author index. Members who have not received copies should make 
application to headquarters. 

The Papers Committee. The Papers Committee is now responsible 
for the technical quality of all papers which appear in the JOURNAL 
whether or not they are presented at Society meetings. The chair- 
man has available the various members of his committee and the 
Associate Editors to serve as readers and censors of papers sub- 

The Papers Committee will be guided by the following regulations: 

(1) All papers which are accepted by the Papers Committee for 
presentation before conventions shall be published in the JOURNAL 
in their entirety, regardless of whether or not they may have been 
published in some part previously. 

(2) Papers which are offered for publication in the JOURNAL will be 
considered on their merits and will either be accepted for publication 
in their entirety or rejected. 

(3) Papers which have been published in other journals which 
are considered to be of interest to our membership may be reprinted 
in our JOURNAL in full or in abstract form as agreed upon between the 
Editor and the Papers Committee. 

The Chicago Section. A meeting was held on December 4, 1930, 
at the offices of the Enterprise Optical Company, 564 W. Randolph 
Street, at which Mr. Schoenberg delivered a paper on "Light." This 
was followed by a showing of the picture Whoopee. 

262 SOCIETY NOTES . [J. S. M. P. E. 

Mr. O. F. Spahr asked if the members would be interested in 
seeing and hearing a sound print being shown in one of the small 
theaters of the rural sections of Indiana. This picture was one of 
the first shown by the theater owner in question, who thought he 
was getting something quite good. The photography, and particu- 
larly the sound, was so poor that many of the members had to be 
reassured that the demonstration was not faked. 

The London Section. Although the officers of the London Section 
have resigned as of December 31, 1930, the section has not been 
disbanded by the Board of Governors. A questionnaire has been 
circulated to the members of the London Section to determine if 
they wish to elect new officers and continue the section. 


In sincere appreciation of the services rendered the Society by 
Mr. Loyd A. Jones, the Board of Governors, at a meeting held 
December 19, 1930, at New York, N. Y., voted unanimously that 
announcement of this appreciation be made in the pages of the 

As chairman of the Journal Committee and Editor pro tern to the 
JOURNAL, Mr. Jones undertook the burden of establishing and setting 
in motion the machinery for changing over the Society's form of 
publication from that of quarterly Transactions to a monthly JOURNAL, 
the first issue of which was published in January, 1930. Mr. Jones 
continued in capacity of editor until a permanent paid editor was 
acquired in December, 1930. These services were donated gratis 
and constitute an example of unselfish devotion to science and the 
motion picture industry. 

May 25-28, 1931, at Hollywood, California 

Headquarters: Roosevelt Hotel, Hollywood. 

The Society has been quoted the following special day rates for the 

Single room with bath $3.00 

Double room with bath . . . . $5 . 00 

Feb., 1931] SOCIETY NOTES 263 

Those desiring a connecting parlor, additional $5 . 00 day rate. 

Your Convention Committee will submit at a later date, complete 
information in bulletin form, on transportation schedules and rates 
over three routes to the West Coast. 

With the exceedingly low summer rates in effect during the con- 
vention dates, you will be afforded an excellent opportunity of at- 
tending our Hollywood meeting by arranging your vacation periods 

An interesting papers and recreational program is assured during 
our stay in Hollywood. 

Preliminary plans of the Papers Committee, in connection with the 
Hollywood convention, are presented under Committee Activities in 
this issue of the JOURNAL. (See page 243.) 

W. C. KUNZMANN, Chairman 


One of the chief reasons why our Society changed its form of 
publication from quarterly Transactions to a monthly JOURNAL was 
to permit the dissemination of information which is not made 
available at our conventions. The transactions of a society merely 
record the proceedings at the society's meetings whereas it is proper 
for a journal to publish any matter pertaining to the welfare of the 

Our Society will thrive only if each member takes a deep interest 
in its welfare. Having the interests of our Society at heart, each 
of you must have suggestions for making our JOURNAL and conven- 
tions of greater value to the industry. It is with this object in 
view, that at a meeting of the Board of Governors at New York City 
on December 19th, it was resolved: "That an open forum be established 
as a new department of the JOURNAL, in which might be published 
letters and communications from members relating to material 
in the JOURNAL or to other matters appertaining to the welfare of the 
Society, subject to the discretion of the Editor and Board of Editors." 

May I suggest correspondence on subjects such as the following: 

(a) Better ways of conducting the conventions. 

(b) Problems for research. 

(c) Problems for investigation by the various committees. 

(d) Discussion of technical papers appearing in the JOURNAL, 
with comments on the success or failure of their application. 

(e) Description of interesting or new developments which have 
come to your attention during your travels, thereby giving all the 
members the benefit of this knowledge. 

(/) Preliminary announcements of investigations and discoveries 
which are to be more fully reported at a later date in formal papers. 

Remember that the Society of Motion Picture Engineers is your 
Society and although many of us are widely separated geographically, 
let us meet monthly in the Open Forum. 

J. I. CRABTREE, President 



Agfa Ansco Corporation 

Audio-Cinema, Inc. 
Bausch & lyomb Optical Co. 

Bell & Howell Co. 

Bell Telephone Laboratories, Inc. 

Case Research Laboratory 

Consolidated Film Industries 

DuPont-Pathe Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theatres Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Pacent Reproducer Corp. 

Paramount-Famous-Lasky Corp. 

RCA Photophone, Inc. 
Technicolor Motion Picture Corp. 

Transactions of the S. M. P. E. 

A limited number of most of the issues of the Transactions is still available. 

These will be sold at the prices listed below. 

Please note that nos. 1, 2, 5, 6, 8, 9, and 10 are out of print 

Orders should be addressed direct to the General Office, at 33 West 42nd Street, 

New York, N. Y. 



































Volume XVI MARCH, 1931 Number 3 


Recent Developments in RCA Photophone Portable Recording 

Equipment P. M. ROBILLARD AND E. B. LYFORD 269 

A Modern Laboratory for the Study of Sound Picture Problems 

T. E. SHEA 277 

The Depth of Field of Camera Lenses with Special Reference to 

Wide Film ARTHUR C. HARDY 286 

Two- Way Television HERBERT E. IVES 293 

A Truck Mounted Laboratory for the Diagnosis of Theater 

Acoustic Defects VESPER A. SCHLENKER 302 

Some New RCA Photophone Studio Recording Equipment. 


Materials for the Construction of Motion Picture Processing Ap- 
paratus. . J. I. CRABTREE, G. E. MATTHEWS, AND J. F. Ross 330 

Aiding the Theater Patron Who Is Hard of Hearing 

F. H. GRAHAM 341 

Test Set for Servicing Sound Projection Equipment 

A. H. WOLFERZ 349 

Cinematography with the Laryngoscope 356 


The Call Announcer: A Telephone Application of Sound- 
Picture Ideas O. M. GLUNT 362 

Committee Activities 368 

Abstracts 371 

Patent Abstracts 377 

Book Reviews 383 

Officers 386 

Committees 387 

Contributors to This Issue 389 

Society Announcements 391 

Open Forum 395 





Associate Editors 




Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members $12.00 per year; to members $9.00 per year; single 
copies $1.50. Order from the Society of Motion Picture Engineers, Inc., 20th and 
Northampton Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 



Summary. This paper describes improvements made in the RCA Photophone 
y ortable Recorder since the publication of the original paper describing this equip- 
ment. The new optical system and galvanometer, which require much less power 
for its operation, are described and illustrated. The new amplifier, considerably 
smaller and lighter than the previous one, is also described. Illustrations and elec- 
trical characteristics are given. This recorder is mounted upon a standard Mitchell 
camera and records by the Photophone variable-area method. The complete equip- 
ment weighs 450 pounds, including carrying cases and all accessories. 

The RCA Photophone portable equipment for sound-on-film 
recording was described in 1929. l It is the purpose of this paper to 
describe the improvements which have been made in the equipment 
since that time. 

Before launching into detailed description of specific parts, let 
us review briefly the general arrangement of this equipment. 
Fig. 1 shows the entire outfit in schematic form. The condenser 
microphone picks up the sound, which is then passed through a 
cable to the amplifier, where it is brought up to a level suitable for 
recording. The sound energy passes through another cable, via the 
battery box, to the recording head mounted directly upon a 
standard Mitchell motion picture camera. The amplifier contains 
all batteries necessary for the microphone and recording exposure 
lamp, as well as for its own power-supply the separate battery box 
supplies only the power necessary for the camera motor and inter- 
phone system. 

Since the publication of the previous paper describing this equip- 
ment, two important links in the chain of apparatus the amplifier 
and the optical system of the recording head have been completely 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** RCA Photophone, Inc., New York, N. Y. 




Since portability is one of the important features of the entire 
equipment, it was felt that the original amplifier might, with profit, be 
reduced in size and weight. The new amplifier case measures only 

FIG. 1. Schematic arrangement of portable recording equipment. 

S l /2 by 18 by 15 in. over-all and weighs but 53 pounds complete 
with all batteries. 

An interior view of the amplifier is shown in Fig. 2. It comprises 
three stages of audio-frequency amplification, and employs four 

March, 1931] 



tubes a UX-864 in each of the first two stages, and two UX-112A 
tubes in push-pull in the final output stage. As may be seen, the 
necessary transformers and impedances are mounted on a shelf with 
the tube sockets, while the accompanying condensers and resistances 
are mounted beneath. The whole is enclosed within a metal can, 
which, with the metal panel, combines completely to shield the am- 
plifier from any sort of extraneous disturbances. 

FIG. 2. Interior view of amplifier with shield removed. 

Flexible leads are brought out through the bottom of the metal 
shield to the batteries, which are carried in the case together with 
the amplifier itself. Fig. 3 shows the amplifier case viewed from 
above, the amplifier being removed. The "B" battery of 180 volts 
and a 7Va volt "C" battery are in the left-hand compartment. An 



8 volt filament battery is carried in the smaller right-hand compart- 
ment, a hinged cover enclosing it and allowing the space above to be 
used for spare tubes, phones, etc. 

FIG. 3. View of amplifier case with amplifier removed, 
showing batteries in place. 



F/LAMENT a/V-O^F $t.eCTOAZ /*VOft$ 

S W/ TCrt & " 7XT/V W #H0S TAT. 

FIG. 4. Panel view of amplifier. 

A panel view of the amplifier is shown in Fig. 4. The plug re- 
ceptacle in the upper left-hand corner is the input, and the one in 
the upper right-hand corner is the output. A rheostat in the lower 
left-hand corner controls the filament supply of the microphone 

March, 1931] 



amplifier, and a similar rheostat in the lower right-hand corner 
controls the current of the recording lamp, indicated by the meter 
directly above it. The signal volume control may be seen left of the 
center. The larger meter in the center of the panel measures all 
the currents, and is controlled by the multiple switch beneath it.. 
The amplifier filament current, amplifier plate current, and micro- 
phone amplifier filament current may be read on this meter, and in 
the fourth switch position the meter may be used as a volume in- 
dicator. Phones may also be used for monitoring by plugging the 
cord tips into the receptacle shown on the panel. 

The circuit of the amplifier is of conventional design. Control of 
volume is effected by a potentiometer across the secondary winding 





FIG. 5. Schematic of optical train. 

of the input transformer. The filament supply of the tubes is con- 
trolled by fixed resistances, and the proper grid biases are all obtained 
from taps on the common "C" battery. The volume indicator is 
operated through a dry rectifier across part of the secondary winding 
of the output transformer and the monitoring phones are supplied 
from the same source. 

Some of the electrical characteristics of this amplifier may be of 
interest. Its input impedance is 250 ohms, designed to work directly 
from a standard RCA Photophone condenser microphone amplifier. 
The output impedance of the amplifier is approximately 1.8 ohms, 
designed to feed directly into the recording galvanometer. The 



over-all voltage amplification of these amplifiers averages from 310 
to 320, corresponding to a gain of approximately 50 db. The 
frequency characteristics compare favorably with those of other 
amplifiers used for similar purposes, and are considerably better at 
extremely high frequencies, averaging 70 per cent of maximum at 
9000 cycles. The total available undistorted power output is about 
80 milliwatts. 


The optical system of the recording head has also been completely 
re-designed. Fig. 5 shows a schematic representation of the optical 

PL A T. 

FIG. 6. Recorder optical system; cover removed. 

train which is employed. The light from the exposure lamp is fo- 
cused by means of the condensing lens onto the mirror of the record- 
ing galvanometer, which rotates slightly around a vertical axis in 
accordance with the fluctuations of the incoming signal. This 
modulated beam of light now travels to the reflecting mirror, and 
is directed back to the aperture plate of the focusing barrel. 

First passing through cylindrical, and then through condensing 
lenses, the latter being similar to the objective lens of a microscope, 
the beam of light is brought to bear upon the film. The important 
new feature of this optical system is that there has been effected a 

March, 1931] 



great economy in the use of the light emitted by the exposure lamp 
so much so that this lamp need now be only of the 4 volt, 0.75 ampere 
type, in contrast to the previously used 5 volt, 4 ampere type. The 
reduction in power is in the ratio of three to twenty watts. The new 
exposure lamps, furthermore, need not be of the pre-focused type, 
as was required in the previous design. They are adjusted by the 
operator of the equipment in his spare time, and may be dropped into 
the correct position in a moment's time, if necessary. 

Fig. 6 illustrates the appearance of the optical system with the 

FIG. 7. Optical system and recorder head mounted on camera. 

protecting cover removed. All the component parts which have 
been described may be plainly seen; especial attention is called to 
the galvanometer, which is of entirely new construction. It is of 

le fully-enclosed, mechanically-damped type, designed by G. L. 

)immick, of the RCA Victor Company. Space cannot be 
jiven for a complete description of this instrument more than to 
that it is more rugged and stable than its predecessor, and in addi- 
tion, requires only about one-third as much power for its operation. 


The cover of the optical system is clamped in place by two thumb- 
screws, and the whole is attached to the recording head by three 
other screws, all easily removable. The appearance of the optical 
system and recorder head, mounted on the camera, is shown in 
Fig. 7, from which it may be seen that the external appearance 
of the completed unit has been but little changed. In this photo- 
graph the optical system is shown with the protecting cover re- 
moved, but with the connections made to it by the separable plug 


1 HANNA, C. R. : "The Mitchell Recording Camera Equipped Interchangeably 
for Variable-Area and Variable-Density Sound Recording," Trans. Soc. Mot. 
Pict. Eng., XHI (May, 1929), No. 37, p. 312. 


MR. KELLOGG: This optical system, designed by Mr. John B. Taylor, of 
Schenectady, has a very significant feature not possessed by other optical sys- 
tems. It does not use a mechanical slit, which means a saving in weight of 25 
pounds. The optical system with a slit requires a lamp of at least 25 watts, 
whereas the slitless optical system just described calls for a lamp consuming only 
3 watts, which can be operated on dry cells or very small storage-battery, instead 
of requiring the heavy storage-battery which would be needed with a 25 watt lamp. 

MR. E. D. COOK: I would like to ask about the actual illumination obtained 
at the film with this type of optical system. 

MR. OFFENHAUSER: With a three-quarter-ampere lamp, in the present optical 
system we can obtain sufficient density at the film to fog it under certain condi- 
tions. Ordinarily we work at a density of 0.9 to 1.0. The light available from 
the optical system is more than sufficient to secure that density with normal 
laboratory treatment. 


T. E. SHEA** 

Summary. Recently there has been provided among the research facilities of 
Bell Telephone Laboratories, Inc., a separate building which is intended solely for 
sound picture research and development work. The prime objects of the laboratory 
are to find out the best methods and technic for employing sound picture recording 
and reproducing apparatus now in use, and of making improvements in record- 
ing and reproduction. The building contains a recording studio, film processing 
plant, and review room, together with testing laboratories. 

There has been completed by the Bell Telephone Laboratories 
during the past year an additional laboratory unit to be used ex- 
clusively for developments relating to sound pictures. It is the 
object of this paper to describe the new laboratory unit and to indi- 
cate some of its aims. 

Motion picture engineers generally believe that the sound picture 
will continue to develop in many ways and for a long time, before it 
may be considered to have exhausted its possibilities. During the 
past several years the attention of the motion picture industry has 
perforce been chiefly devoted to the providing of satisfactory re- 
cording and reproducing systems in studios and theaters, and to the 
creation of a satisfactory technic for the use of such systems. As 
sound apparatus has become better understood by the industry, 
better results have been obtained with it through the fuller reali- 
zation of the qualities it inherently possesses. 

The introductory period of sound pictures having largely passed, 
we may expect a period of exploration, in which recording and re- 
producing systems will be asked to meet more difficult requirements 
so that the art they serve may grow in its scope. As new conditions 
arise, it will be necessary to subject apparatus to exhaustive tests 
to determine its limitations and capabilities in any given circum- 
stances, to give experimental trial to improvements in recording 
and reproduction intended to overcome limitations, and to work out 

* Presented at the Fall 1930 Meeting, New York, N. Y. 
** Bell Telephone Laboratories, Inc., New York, N. Y. 




[J. S. M. P. E. 

revised technics for employing apparatus for recording and repro- 
ducing sound. 

The central thought in the planning of the laboratory unit de- 
scribed herein has been to provide for experimental control of every 
factor influencing sound quality, from set and microphone to loud 
speaker and auditorium. With such an arrangement, the influence 
of any change in recording, processing, or reproducing can be ex- 
amined alone, without the confusion wrought by other changes. 
When one considers the numerous types of problems involved in 
sound picture developments acoustical, electrical, mechanical, 

FIG. 1. General view of sound stage. 

optical, and chemical and the succession of processes involved in 
recording and reproducing, the importance of this principle is evident. 
It is evident, as well, why experimentation under the handicap of 
production conditions is necessarily difficult. 

Accordingly, the building contains the physical essentials of 
studio, processing laboratory, and theater. The recording facilities 
comprise a sound stage, monitoring room, dressing rooms, scoring- 
projection room, and wax and film recording rooms, with asssociated 
amplifying, testing, and power supply equipment. The photo- 
graphic facilities include processing equipment, printing machines, 

March, 1931] 



editing equipment, and special optical and photographic testing 
laboratories. A review room or small theater with associated pro- 
jection equipment provides for the reproduction of sound and picture. 
Offices for the staff and a film-storage vault complete the laboratory 
unit. Entire experimental sound pictures can therefore be pro- 
duced in this building, or any step in the production and exhibition 
of sound pictures separately studied. 

A description of the principal features of the laboratory unit follows. 

General. The building is located at 151 Bank Street, New York, 
N. Y., adjacent to the principal buildings of the Bell Telephone 

FIG. 2. The monitoring room. 

Laboratories. It is a three-story, brick building, of fire-proof con- 
struction throughout. It occupies a frontage of 49 feet, a depth 
of 118 feet, and has a height equivalent to five normal stories. In 
the construction of the building, the necessity for excluding noise 
and dirt has been recognized, especially in view of the city location 
adopted. The building contains an air-conditioning plant supplying 
all rooms with conditioned air, and especially caring for the ventila- 
tion and cooling of the sound stage, the cleanliness of recording 
rooms, and the control of temperature and humidity in film proc- 
essing rooms. 

280 T. E. SHEA [j. s. M. P. E. 

Sound Stage. The sound stage (Fig. 1) occupies the major por- 
tion of the third floor, and is 47 feet wide, 70 feet long, and 25 feet in 
height. It is therefore of sufficient size to permit the erection of 
ample motion picture sets for experimental purposes. Acoustic 
treatment of the stage consists of rock-wool covering on the walls 
and ceiling, together with adjustable monk's-cloth drapes on the 

FIG. 3. The monitoring position on the balcony for control of 
recording volume. 

end walls. On the side walls are located power outlets for set light- 
ing, microphones, camera motors, and a signaling and inter-com- 
municating system. A track system on the ceiling expedites the 
moving of equipment and set materials. 

Monitoring Room. The remainder of the third floor is given 
over chiefly to a monitoring room and balcony. (Figs. 2 and 3.) At 
the monitoring position on the balcony (Fig. 3), the action on the 



set may be watched while the sound being recorded is projected into 
the monitoring room through loud speakers. (Fig. 2.) Control of 
recording volume takes place at the monitoring position, and by 
means of the intercommunicating and signaling system the monitor 
keeps in touch with all parts of the recording organization. The 
monitoring room is treated acoustically with rock-wool, but is con- 
siderably more "live" than the sound stage. Monitoring may also be 
done in a monitoring booth located on the sound stage, when de- 
sired. Interconnecting doors between stage and monitoring room 

FIG. 4. The film recording room. 

may be thrown open in such a way as to permit ''long shots" to be 
taken the entire length of the building. 

Scoring-Projection Room. Under the monitoring balcony and 
between the sound stage and monitoring room is a scoring-projection 
room from which picture or sound, or both, may be projected into 
either sound stage or monitoring room, when these rooms are used 
for scoring or re-recording. 

Dressing Rooms. For the use of artists employed in experimental 
work, six dressing rooms have been provided on the second floor, 
including group and individual dressing rooms. 



[J. S. M. P. E. 

Recording and Power Rooms. Film and wax recording rooms 
are installed on the second floor (Figs. 4 and 5) and include, in each 
case, two recording machines, together with control and announcing 
equipment. Amplifying and testing equipment occupies a room 
adjacent to the recording rooms. Two distributor systems for 
interlocking and controlling recording machine and camera motors 
are also available, as well as storage-battery power-supply for the 
recording sy stem . 

FIG. 5. The wax recording room. 

Film Processing Plant. To insure adequate experimental control 
of the processing of film recordings, complete printing and processing 
facilities have been included on the first floor of the new building. 
Two automatic and continuous processing machines are provided 
for negative and positive development. (Figs. 6 and 7.) Rack and 
tank equipment also exists. The output capacity of this plant is 
larger than is normally required by the experimental work, but a 
primary requirement is that the processing equipment employed 
shall be consistent with practice in the industry. Automatic 
control of the humidity and temperature of the air in the processing 

March, 1931] 



rooms is available, and automatic recording equipment checks this 
control. Two printing machines of standard make are installed. 
Film-editing facilities are located adjacent to the processing rooms. 

FIG. 6. Processing machine (development end). 

In operating this plant, the utmost care is taken in supervision and 
maintenance to insure consistent and scientific results. 

Optical and Photographic Laboratories. As an aid to optical 
and photographic investigations associated with processing, and 



[J. S. M. P. E. 

with recording and reproducing, laboratories equipped with optical 
and photographic testing apparatus are provided on the second 

Review Room. A small theater or review room is located on the 
first floor, and offers means for testing, by the reproduction of sound 

FIG. 7. 

Processing machines (spray tanks and drying cabinets). 


or picture or both, the results of recording and processing. The 
projection equipment is of the standard theater type, and is main- 
tained at a high level of performance. 

Film Vault. On the roof of the building is a film vault designed 
to accommodate about 1,500,000 feet of film. Both nitrate and 
safety type films are employed and stored. 


Film Handling. In general, care has been taken in the construc- 
tion of the building and the arrangement of operating practices to 
do whatever is reasonably possible to minimize hazards due to the 
handling of inflammable film. 

Supplementing the facilities of the laboratory building described 
above, a portable recording laboratory of the newsreel truck variety 
permits the prosecution of outdoor experimental work. The truck 
is so arranged that when not used to house recording equipment, 
measuring apparatus of various kinds can be operated in it. 

Finally, contributing to the work of the laboratory unit are many 
individual design and testing laboratories within Bell Telephone 
Laboratories, which are concerned either entirely or in part with 
sound picture developments. 



Summary. An analysis is made of the factors governing the apparent depth oj 
field in a picture as judged by a person seated in the audience. The greatest depth of \ 
field results, for the same final magnification on the screen, when the focal length oj 
both the camera and projector lenses are kept as short as possible. This procedure \ 
results in a greater magnification in projection, and the graininess of the film begins \ 
to be apparent if the process is carried too far. ' Actually the limit of magnification 
with 35 mm. film has been nearly reached with existing materials. 

It is shown in this paper that the use of a wider film for both negative and positive 
does not alter the depth of field, provided the same over-all magnification is used. 
Similarly, making a large negative and a smaller print has no effect on the depth oj 
field under comparable conditions. 

By the very nature of optical imagery, a lens is capable of formin 
a sharp image of only a single plane of the object space. In practice, 
however, such factors as the aberrations of the lens or the grainine 
of the film establish a limit for the useful sharpness, so there is a 
certain depth of field that may be said to be in sharp focus. The depth 
of field is sometimes called the depth of focus, but the latter term 
a different significance in optical terminology. 

The lack of depth of field of a lens is familiar to anyone who has ev 
attempted to make photographs with lenses of high relative aperture, 
but there is nevertheless a great deal of misinformation on this subject 
This seems to be a consequence of the custom of judging the depth o 
field from the results of photographic tests, which are seldom con 
ducted in such a manner as to yield results that are really significant 
Even if they are, a lens of poor quality has apparently a greater dept 
of field than a well-corrected one, and the experimental method o 
determining the depth of field may therefore be very misleading. I 
is possible to treat this subject theoretically and, as it happens, th 
rigorous treatment is -less complicated than the approximation tha 
is sometimes made. 

* Received by the Editor November 22, 1930. 
"* Massachusetts Institute of Technology. 


This subject is particularly timely because of the current discussion 
icerning wide film. The effect on the depth of field, when photo- 
graphing a subject on a wider film, is not immediately apparent. 
Nor is it apparent that the depth of field may be altered by making a 
large negative and printing by optical reduction on standard film. 
The purpose of this paper is to consider these questions in some 
detail, but before this can be done, a certain amount of optical theory 
must be developed. 


The depth of field of any lens or optical system is given rigorously 
by the two expressions 


where d\ represents the depth of field on the far side of the object- 
plane in sharp focus and d z represents the depth of field on the near 
side. The total depth of field then is 

d = d, + h . 

In the above equations, r represents the radius of the permissible 
circle of confusion, p is the distance from the entrance-pupil of the 
lens to the object-plane on which the camera is focused, m is the 
magnification of an object in this plane on the film, and p is the radius 
of the entrance-pupil of the lens. 

An erroneous estimate of the depth of field of a lens is sometimes 
made on the basis of the so-called hyperfocal distance. This is the 
minimum distance of an object-plane on which the lens can be 
focused and still have objects at infinity appear sharp. In other 
words, for this condition, the far depth di is infinite. From equation 
(1), it follows that this condition will obtain when 

mp - r = 0. (3) 

Now, in. the Newtonian form of the lens equation, 

where x is the distance of the object-plane in sharp focus from the 

288 ARTHUR C. HARDY [j. S. M. P. E. 

first focal point of the lens. On substituting for m in equation (3), 
we have 

*-, (4) 

where x is the hyperfocal distance measured from the first focal point 
of the lens. Equation (4) can be written in terms of the// number of 
the lens, since this quantity is the ratio of the focal length to the 
diameter of the entrance-pupil. On substituting, we have 


When equation (3) is satisfied, equation (2) shows that the near 

<*.-! (6) 

Hence, when a lens is focused on the hyperfocal distance given by 
equation (5), all objects are in sharp focus from infinity to a point 
half-way between the object-plane in sharp focus and the entrance- 
pupil of the lens. 

Now, a short hyperfocal distance indicates a great depth of field 
when the camera is focused on the hyperfocal distance. It is some- 
times concluded from equation (5), therefore, that the depth of field 
of a lens varies inversely as the// number and inversely as the square 
of the focal length. This argument takes no account of the fact that 
the size of the image varies with the focal length, and that a smaller 
circle of confusion is required for comparable quality in a small pic- 
ture than in a large one. Furthermore, the lack of depth of field is 
seldom troublesome when the camera is focused on an object at the 
hyperfocal distance, but rather when it is focused on a nearby object. 
Under the latter conditions, the quantity r in the denominator of 
equations (1) and (2) becomes negligible compared with the quantity 
mp. Hence equations (1) and (2) become simply 


and the total depth of field is 

d, = ; (8) 




The ratio p/p in the above equation can be transferred to correspond- 
ing quantities in the image-space by means of the well-known relation- 
ship in optical theory that 


p p 

where p' is the distance of the film from the exit-pupil of the lens and 
p' is the radius of the exit-pupil. Equation (9) may then be re- 
written as follows: 

d = * 4- d* = | . (10) 

Now, any comparison of the depth of field of two lenses must be 
made on a basis that insures the same exposure in both cases, since 
manifestly any desired depth can be obtained by reducing the lens 
aperture. It is a well-known fact that the amount of illumination on 
the film in the image of an extended object is determined by the ratio 
p'/p'. 1 Assuming a constant value for this ratio, the depth of field 
is seen from equation (10) to vary directly with the permissible size 
of the circle of confusion r and inversely as the square of the magni- 
fication. This result is independent of the particular form of the 
lens. In other words, any claim that one lens has a greater depth of 
field than another is absurd. If experimental tests seem to indicate 
a difference between lenses, either the two lenses were not used at the 
same effective aperture and magnification, or the image quality of one 
is inferior to that of the other and its depth only appears to be greater. 

The lack of depth of field is apparent to the motion picture audi- 
ence when the size of the circle of confusion on the screen exceeds a 
certain limiting value. Let us designate by R the radius of the 
largest permissible circle of confusion on the screen. Then 

R = rm p m s , 

where m p is the magnification between the negative and positive in 
printing (in contact printing this quantity is 1) and m s is the magni- 
fication of the film on the screen in projection. Substituting for r in 
equation (10), we have 

. ^ . (11) 

Let us assume now an object or actor of height h in the plane on which 
the camera is focused. The corresponding height of the image on the 
screen is 

H = hmm p m, . (12) 

290 ARTHUR C. HARDY [j. s. M. P. E. 

Let us designate the over-all magnification between the object and 
its screen image by M y where 


M = -r = mm p m t . (13) 

With this substitution, equation (11) becomes 

^. (14) 

We see, therefore, that for a fixed value of R and p'/p' t the depth of 
field, as seen by the audience, varies inversely as the original magni- 
fication in the camera and the over-all magnification M. In other 
words, it is just twice as hard to obtain sufficient depth when the 
actor's head is to be ten feet high on the screen as when it is only 
five feet high. The advantage of making m small will be dealt 
with presently. 


Let us consider the case of standard 35 mm. practice where both 
the negative and positive film are of this width and the printing is 
done by contact. Equation (14) shows that, for a fixed over-all 
magnification M, there is a definite gain in making the magnifica- 
tion m, in taking, as small as possible. This implies either using 
camera lenses of short focal length or placing the camera at a great 
distance from the actors. For the same over-all magnification M, 
equation (13) shows that m s must be increased in proportion to the 
decrease in m. In other words, the greatest depth of field is seen to 
result by making the original negative with as low a magnification as 
possible and re ying on subsequent enlargement to provide the re- 
quired over-all magnification. The limit to the subsequent enlarge- 
ment is set by the graininess of the negative material. Unfortun- 
ately, this limit has been reached with 35 mm. negative film, as the 
magnification in the projector is already so high that any further 
increase makes the graininess decidedly objectionable. We must 
conclude, therefore, that the depth of field for a given effective lens 
aperture p'/p' is about as great as it can ever be made with 35 mm. 
film unless the graininess of the film can be reduced enough to permit 
greater magnification in projection. 

Let us now consider the effect of making the original negative and 
release prints on a wider film. For the sake of convenience, let us 

March, 1931] DEPTH OF FIELD OF LENSES 291 

assume the film to be 70 mm. in width, or twice as wide as the 35 mm. 
standard. There are several possible ways of utilizing this increased 
width, but most producers seem to regard the wider film as an oppor- 
tunity to include more action on a larger screen, the size of images on 
the screen remaining approximately as at present. If this plan is 
followed, it is obvious from equation (14) that the depth of field with 
wide film, at the same over-all magnification M and the same magni- 
fication in projection, is identical with that obtained in 35 mm. prac- 
tice. This implies the use of camera and projector lenses of the same 
focal length as at present. If, on the other hand, larger images are 
projected on the larger screen, the increased over-all magnification M 
can be obtained only by increasing either m or m s . It is impossible 
to increase m s without increasing the appearance of graininess. 
Hence, any increase in M must be the result of increasing m, and 
equation (14) shows that this procedure will decrease the depth of 
field. This is not exactly true, because a somewhat larger circle of 
confusion can be tolerated with a larger screen. Nevertheless, the 
fact remains that larger images on the screen are obtainable only by 
sacrificing depth of field. 

Consider now the case where the negative is 70 mm. in width and 
the release prints are 35 mm. in width, the printing being done by 
optical reduction. Since the quantity m p in equations (12) and (13) 
does not appear in equation (14), it follows that this reduction process 
neither increases nor decreases the depth of field when the other condi- 
tions are met that is, when the same magnification m is used in the 
camera and a final image of the same size is projected on the screen. 
Equation (13) shows that when m p is one-half, as it is approximately 
under these conditions, the magnification in projection m s must be 
twice as great to keep the over-all magnification M the same. It 
is claimed, with some justice, that this reduction process reduces the 
graininess and that the magnification in projection nt s can therefore 
be increased over what is possible when the print is made by contact. 
If the reduction in graininess is one-half, so that the magnification in 
projection can be doubled, the depth of field of pictures produced in 
this way is the same as with the two methods that have been discussed 
previously. It may be remarked in passing that it is no more difficult 
to design a projection lens to cover the 35 mm. film than one to cover 
the 70 mm. film if they are of the same relative aperture, but, with the 
same relative aperture, the illumination on the screen with the 35 mm. 
film will be approximately one-fourth as great. In addition, pro- 


jection from the smaller film at a higher magnification imposes more 
severe requirements on the steadiness of the film in the gate. 


1 See, for example, "The Distribution of Light in Optical Systems," A. C. 
Hardy, Journal of the Franklin Institute, Vol. 208, No. 6, December, 1929. It 
may be remarked in passing that the //number is a measure of the illumination 
on the film only when the lens is focused on an object at infinity. 



Summary. An experimental two-way television system in combination with 
a telephone service has been installed between two buildings in New York. With this 
system, two people can both see and talk to each other. It consists in principle of 
two complete television systems of the sort previously used for one-way transmission. 
Scanning is accomplished by the beam-scanning method using disks containing 72 
holes. Purple light, to which the photo-electric cells used are quite sensitive, is em- 
ployed for scanning, and a yellow-green light is used for illuminating the television 
booth. High-intensity neon lamps are used with a condenser lens disk at the receiv- 
ing end to give an image brilliant enough to be seen without interference from the 
scanning beam. A frequency band 40,000 cycles wide is required for each of the two 
television circuits. Synchronization is effected by a 1275 cycle alternating current, 
controlling synchronous motors rotated 18 times per second. Speech is transmitted 
by microphones and loud speakers concealed in the television booths so that no tele- 
phone instrument interferes with the view of the face. 

Ever since the initial demonstration of television both by wire and 
by radio at the Bell Telephone Laboratories in 1927, experimental 
work has been steadily pursued in order to learn the problems and 
possibilities of this newest branch of electrical communication. The 
latest development to be demonstrated is that of two-way television 
as an adjunct to the telephone. As a result of this development work, 
there is now set up an experimental and demonstration system oper- 
ating between the headquarters building of the American Telephone 
and Telegraph Company at 195 Broadway, and the building of the 
Bell Telephone Laboratories at 463 West Street, New York City, 
two miles away. This system makes it possible to experiment with 
a method of communication in which the parties engaged not only 
speak with each other, but at the same time see each other. Study 
of this system will serve to give information on the importance of 
the addition of sight to sound in communication and will give valuable 
experience in handling the technical problems involved. 

In principle the two-way television system consists of two complete 

* Presented at the Fall 1930 Meeting at New York, N. Y., at a session held 
at the Bell Telephone Laboratories 
** Bell Telephone Laboratories. 




[J. S. M. P. E. 

systems of the same sort as those used for one-way transmission in 
the demonstration from Washington to New York City in 1927. In 
place of a scanning disk and set of photo-electric cells at one end for 
generating the television signals, and a single disk and neon lamp at 
the receiving end for viewing the image, there are in the two-way 
system, two disks at each end and a bank of photo-electric cells and a 
neon lamp at each end. One of the disks, which, in the system as con- 
structed, is 21 inches in diameter, serves to direct the scanning beam 
from a high intensity incandescent lamp onto the face of one of the 






FIG. 1. Schematic diagram of one terminal of the two-way television 


parties to the conversation. (Fig. 1.) Fourteen photo-electric cells, 
arranged in banks on either side, before and above the person's face, 
pick up the reflected light and generate the television signals. The 
second disk, which is 30 inches in diameter, is placed below the sending 
disk and exposes through its holes the neon lamp, which the observer 
sees through a magnifying lens in a position slightly below that of 
the scanning beam. This neon lamp is, of course, actuated by the 
signals coming from the distant end of the system, where there is a 
similar arrangement of two disks, photo-electric cells, and neon lamp. 
The two parties to the conversation take their places in sound- 

March, 1931] 



proof and light-proof booths, where, sitting in front of the photo-elec- 
tric cells, they look at the image of the person at the other end at the 
same time that the scanning beams play over their faces. (Fig. 2.) A 
problem of illumination is immediately encountered in that the scan- 

FIG. 2. Interior of television booth showing position of incoming 
image, and just above it, the hole through which the scanning beam is 
projected. The photo-electric cells are behind the glass panels. 

ning beam is of necessity intensely bright and tends to dazzle the eyes 
to the extent that the somewhat faint neon lamp image is hard to see. 
This difficulty is met by using light for scanning to which the human 
eye is relatively insensitive, and by selecting types of photo-electric 



[J. S. M. P. E. 

cells which are highly sensitive to this special light. Part of the 
cells are of potassium, highly sensitive to blue light; the others are of 
caesium, highly sensitive to red light. The scanning light is a mixture 
of red and blue from the ends of the spectrum. The scanning beam 

FIG. 3. Side view of synchronous motors and scanning disks. The 
incandescent lamp furnishing the scanning light is shown behind the 
upper disk; the neon lamp which translates the incoming signals into 
light is shown behind the lower disk. 


is perceived only as a spot of purple light in the lens which projects 
it, not bright enough to interfere with clear vision of the neon lamp 
which provides the image of the person located at the distant end. 
Adequate general illumination of the booth is provided by lamps 
furnished with yellow-green filters, transmitting light to which neither 
type of photo-electric cell is sensitive. 

In the original demonstrations of one-way television, scanning disks 
were used which had fifty holes arranged in a spiral. With this 
number of holes, it is possible to secure a definitely recognizable 
representation of the human fa.ce. It was decided, however, that 
for the two-way system a degree of definition should be provided such 
that faces were rendered in an entirely recognizable and satisfactory 
manner. Accordingly, the number of scanning holes has been in- 
creased to seventy-two, which provides just twice the number of 
image elements. The transmission band is, of course, doubled by 
this change, requiring wire connections of considerably higher quality 
than heretofore. When a seventy-two hole scanning disk is used the 
component frequencies of the image signal encompass a range of from 
10 to 40,000 cycles per second, whereas intelligible speech may be 
reproduced by a signal wave whose component frequencies cover a 
range of 2500 cycles per second. This comparison roughly indicates 
how much more difficult it is to transmit high quality television images 
than it is to transmit ordinary speech. In general, the electrical 
features of the apparatus are similar to those previously used, al- 
though in the interval improvements and refinements have been 
made in many directions. (Fig. 3.) 

Light reflected into the photo-electric cells gives rise to an alternat- 
ing electric current whose effective value is of the order of a ten- 
thousand-billionth ampere. The neon glow lamp on which the image 
is received at the distant station reproduces the image satisfactorily 
when the effective value of the alternating current is of the order of 
one-tenth ampere. This thousand-millionfold increase in current 
variation, considerably greater than was required for the earlier one- 
way system, is effected by amplifiers in which the vacuum tubes are 
coupled by condensers and resistances. The tubes, which operate 
at low energy levels, are shielded against electrical, mechanical, and 
acoustical interference. 

For the transmission of images between 463 West Street and 195 
Broadway, the appropriate stages of the amplifier system are coupled 
by special transformers to telephone cable circuits equipped with spe- 

298 HERBERT E. IVES [J. S. M. p. E. 

cial distortion correcting networks which are capable of transmitting 
the extremely complex current variations without distortion. The 
amounts of distortion inherent in other parts of the system are either 
kept small by design or annulled by means of correcting networks. 
An indispensable part of a television system is the means for holding 

FIG. 4. Microphone and loud speaker used for two-way conversation, 
in conjunction with the two-way television system. These are ordinarily 
concealed by the front wall of the booth. 

several scanning disks accurately at the same speed. For the two- 
way television system, a simplified and improved synchronizing ar- 
rangement is used. The disks at the receiving and transmitting ends, 
which rotate at a speed of 18 revolutions per second, are synchronized 
by means of a vacuum tube oscillator located at one end of the line 

March, 1931] Two- WAY TELEVISION 299 

and delivering a frequency of 1275 cycles per second at a low power 
level. This frequency is transmitted over a separate pair of wires, 
and controls, at the receiving end, by means of vacuum tubes, the 
field strength of the motor thereby holding its speed exactly propor- 
tional to the frequency. In the same way, the speed of the motor 
at the transmitting end is controlled by a similar vacuum tube cir- 
cuit so that its speed is also proportional to the frequency of the same 
oscillator, and thus the motors driving the scanning disks at both ends 
of the line are held in synchronism. By using a frequency of 1275 
cycles per second, the degree of synchronization is held within suf- 
ficiently close limits to keep the picture at the receiving end central 
within its frame to within a small fraction of the picture width. 
Novel features of this synchronizing system are the use of mechani- 
cally damped couplings between the disks and motor shafts, for im- 
proving the steadiness of the image, and of an electrical phase shifter 
for framing the images. 

The acoustic portion of the two-way television system is unusual 
in that it permits simultaneous two-way conversation without requir- 
ing either person to make any apparent use of telephone instruments. 
It is obviously desirable to arrange the acoustic system in this way 
because the ordinary telephone instrument conceals part of the face 
and would thus prevent the system from approximating the conditions 
of ordinary face-to-face conversation. The elimination of telephone 
instruments is accomplished by using a microphone sensitive to 
remote sounds and a loud speaker concealed near the television image 
at each station. (Fig. 4.) The microphone at one station is connected 
through suitable vacuum tube amplifiers and a telephone circuit to the 
loud speaker at the other station. This permits conversation in one 
direction while a similar connection between the other microphone 
and loud speaker permits conversation in the other direction. The 
persons using the system then communicate as if face to face, with 
no telephone system apparently involved. 

In order that the transmitted sounds be familiar and natural, distor- 
tion in the sound transmission system has been reduced to a minimum. 
The microphones are of the condenser type used extensively in radio 
broadcasting and sound picture recording. Being of small size, they 
are readily concealed near the television image in the most advan- 
tageous position for picking up the voice. The loud speaker, also 
of small size but capable of reproducing a broad frequency range, is 
likewise concealed near the television image, so that the sounds 



[J. S. M. P. E. 

produced appear to emanate from the image itself. This loud speaker 
is of the moving coil type with a small piston diaphragm. 

In any system such as that described, the microphone is not capable 
of distinguishing between the sounds from the local speaker or from 

FIG. 5. Scanning disk cabinet and control panels for two-way 
television at 195 Broadway. 

a speaker at the remote end of the circuit reproduced locally by the 
local loud speaker. If the sounds from the local loud speaker should 
be impressed upon the local microphone in sufficient magnitude, 
"singing" would result, and the system would be no longer operable. 
To prevent this the microphone and loud speaker are installed in care- 

March, 1931] TWO-WAY TELEVISION 301 

fully chosen positions, and the inner surfaces of the sound-proof 
booths are specially treated to prevent as much as possible the reflec- 
tion of sounds from the walls into the microphone. Under these con- 
ditions, the attenuation of transmitted sounds is of about the same 
magnitude as would be experienced if the listener were, say, 10 or 12 
feet away, but in the same room. This acoustic illusion of distance 
is in harmony with the visual appearance of the television image. 

In addition to the television synchronizing and acoustic circuits, 
others are provided for signaling and monitoring purposes. Matters 
are so arranged that an operator can see both the outgoing and in- 
coming image. (Fig. 5.) By means of movable lens and prism sys- 
tems he can be assured that the scanning beam is properly directed to 
correspond to the height of the observer and that the received image 
is properly placed for observation. 

Operating arrangements are made so that the two parties to the 
conversation, after taking their positions in the booths, do not see or 
hear each other until adjustments are made, whereupon the operators 
expose the images and connect the talking circuits simultaneously. 
The experimental service is arranged on an appointment basis. 
The two parties to the conversation, having arranged with attendants 
at the two stations for their time, proceed to the respective booths, 
where they are ushered into chairs in position before the photo-electric 
cells and instructed as to the operation of the system. Immediately 
after the attendant closes the booth door the operators make the 
necessary adjustments, and the simultaneous sight and sound 
communication is carried on until, upon the parties leaving their 
chairs, the connections are interrupted. 



Summary. Experience in acoustic diagnosis by application of Sabine's 
formula indicates the need of more comparative data for the solution of acoustical 
problems in theaters. For this purpose, the acoustical truck described in this paper 
was developed. The various uses of the truck and apparatus housed by it in studying 
reverberation, distortion, and transients, frequency characteristics, etc., of theaters 
are described. Oscillo grams obtained in a number of such tests are presented. 

A year and a half ago the Vitaphone Corporation decided to accept 
some responsibility for the correct transmission of sound in the thea- 
ters from the loud speakers to the audience. The officials and en- 
gineers had learned through disheartening experience that sound 
which is properly recorded in the studios may become almost unin- 
telligible when reproduced under certain conditions. 

Previous experience in acoustic diagnosis by means of Sabine's 
formula only proved that much more quantitative data are needed 
for the solution of acoustical problems in theaters. A knowledge of 
the reverberation period alone is not sufficient. It became evident 
that the required specific data on a particular theater could be ob- 
tained only by means of the very best electro-acoustic apparatus. 
The effects of domes, barrel ceilings, curved walls, balcony cavities, 
as well as the characteristics of the loud speakers, had to be known 
with some degree of accuracy for each theater. The demands for 
low expense in acoustic correction made it very necessary that a 
complete survey be made. 


With these conditions in mind an "acoustic truck" was developed 
and designed for making more complete surveys than those which 
have been possible heretofore. 

An interior view of the acoustic truck is shown in Fig. 1. The frame 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Vitaphone Corporation, Brooklyn, N. Y. 



at the right carries an oscillator, an oscillograph and its motor, vari- 
ous transformers, thermocouples, meters, and frequency modulators. 
The upper cabinet at the left contains spare parts and other acces- 
sories. The lower cabinet is a desiccator for four condenser micro- 
phones and their associated amplifiers. The rack immediately behind 
carries the transmitting amplifiers, frequency-calibrating panel, 

FIG. 1. Interior view of the acoustic truck taken from the rear. 

switching panel, and relay. A small light-proof booth between the 
driver's seat and the transmitting amplifier rack is equipped with 
film, fixing tanks, and dark-room lamp. The reels for the cables to 
the microphones, speakers, volume indicator, telephones, and power- 
supply outlets are mounted outside under the rear doors. 

304 VESPER A. SCHLENKER [j. s. M. P. E. 

When an acoustic survey of a theater is to be made the truck is 
parked at the curb near the rear door. The loud speakers are mounted 
on the stage near the picture screen and their cables are run in from 
the reels. The microphones and cables are likewise taken into the 
theater and placed in position. A telephone line is unreeled and 
drawn in for the necessary communication between the auditorium 
and the truck. The 110 volt, a-c, power-supply cable is also connected 
to an outlet in the theater in order to supply the truck with power for 
the transmitting amplifiers. 


In the reverberation test a single-frequency tone is modulated over 
a half octave by means of a frequency modulator connected to the 
oscillator. This warbling tone is projected into the theater by means 
of the transmitting amplifiers and the loud speakers on the stage. 
When a steady-state condition has been reached the tone is interrupted 
electrically by means of a relay. Simultaneously, the shutter of the 
oscillograph is opened and the decay of the sound is photographed 
as shown in Fig. 2. Two oscillograph traces are employed. Fig. 3 
is a block diagram of the apparatus used for measuring reverberation. 
The upper portion represents the transmitting equipment and the lower 
portion the receiving equipment with its associated microphones, 
panels, amplifiers, and oscillograph vibrators. 

The output of the loud speakers is picked up by the microphones, 
passed through the panel P 2 and amplifier A 2> and thence to the oscil- 
lograph Vz. The amplifier A 3 is used to monitor the output of ampli- 
fier A z and is adjustable in 3 db. steps of gain above A 2 , the attenuator 
x being provided for this adjustment. 

The trace obtained from V\ is exactly like that obtained from Vi, 
except for the amplitude, which in general is greater. The two 
traces so obtained are shown in Fig. 2. 

If the level of V\ is adjusted to, say, 24 db. above that of V 2 , it is 
clear that the time required for V\ to be attenuated to the origi- 
nal value of V 2 is a measure of the reverberation period of the theater 
being studied. That is, referring to Fig. 2, if the amplitude of the 
trace V\ at the instant A is the same as that of trace Vz at the instant 
B, it is clear that during the time interval t, the drop must have been 
equal to 24 db., which is the difference in level of the two amplifier- 
oscillograph channels. It is a simple matter to calculate the time for 
a 60 db. drop, which is generally used as the period of reverberation. 

March, 1931] 



FIG. 2. Oscillograph traces obtained in the reverberation test. 










/4"t P 







f S*v 

^ t 










: r: 



FIG. 3. Block diagram of apparatus used for making reverberation mea- 
surements. Various switching arrangements are provided for but are not 
shown in the diagram. 



FIG. 4. Traces obtained in test of frequency characteristics. 

FIG. 5. Traces obtained in simple study of echoes, using the explosive signal. 




Frequency characteristics can be taken by causing the beat-fre- 
quency oscillator to sweep through the entire audible range. Fig. 4 
shows the traces obtained when the output of the transmitting ampli- 
fiers is connected through a resistance pad to the input of the receiv- 
ing amplifier. The half-octave bands are indicated. A comparison 
of the two traces will serve to show that satisfactory characteristics 
covering oscillator, transmitting amplifiers, receiving amplifiers, and 
oscillograph vibrators are obtained. 

FIG. 6. Traces showing the occurrence of echoes in a theater. 

It follows that the characteristic of any part of the theater equip- 
ment may be determined by inserting it in place of the resistance pad. 
Furthermore, the characteristic of the theater equipment as a whole 
may be determined by substituting for the oscillator a sound disk or 
film as was done in obtaining the traces of Fig. 4. The disk or film 
can be played in the ordinary manner when the microphone is placed 
in the auditorium. The resulting oscillogram will give the over-all 
frequency characteristic. 


[J. S. M. P. E. 


In theater acoustics the location of the source of sound is fixed so 
that an opportunity for locating material to the best advantage pre- 
sents itself. In this respect the acoustics of theaters differs from that 
of other auditoriums where the source is not confined to a fixed loca- 
tion. In order to properly locate the acoustic treatment it is obvious 
that more knowledge of the acoustic contributions of the various 
surfaces of the interior should be known. Important information 
of this kind is acquired from an explosive signal which is set off on the 

FIG. 7. 

Traces obtained by using the "synthetic syllable" in an untreated 

stage in front of the loud speakers. With two vibrators connected 
to the outputs of two independent channels it is possible to record on 
the same oscillogram the direct and multiple reflections picked up by 
two microphones. 

Referring to Fig. 5, which gives traces obtained out-of-doors with 
this arrangement, the two microphones, MI and M z , were set up on a 
flat roof with only one small reflecting wall in the immediate vicinity. 
This represents a very simple case of echo-sounding, in which the 
image is first located and then the reflecting surface. It should be 

March, 1931] 



observed that the signal itself covers a very short period of time com- 
pared with the time-interval between the direct sound and its echo. 
When this test is applied to a theater the resulting oscillograms are 
much more complicated, as indicated in Fig. 6. The upper trace 
MI represents the sound in the balcony at the rear of this particular 
theater while the lower trace M$ is the sound picked up in the or- 
chestra near the front. It will be noted that a very definite echo 
exists in the front of the house. 

FIG. 8. Traces obtained using the "synthetic syllable" in a theater after 
acoustic treatment. 


Further information can be obtained by employing a single syl- 
lable of speech. For analytical purposes a syllable can be simulated 
by a single-frequency pulse. The length of the pulse can be varied if 
necessary, but three-hundredths of a second is as short as any speech 
sound used by the average speaker. The frequency can be varied 
over the audible range to include the various frequency components. 
Reflections and echoes of this signal when projected from the 
loud speakers can be recorded on oscillograms. The results of such a 
test in a theater before treatment are shown in Fig. 7. The lower 



[J. S. M. P. E. 

trace represents the sound picked up by a microphone placed four 
feet in front of the speakers. The upper trace is due to another micro- 
phone at the rear-center of the theater. After acoustic improvement 
the same test was repeated giving the condition indicated in Fig. 8. 
It is evident that the pronounced series of echoes has been effectively 

Intensity distribution in the various seats of a house may be de- 

FIG. 9. 

Traces of speech from microphones at two different positions in the 
theater before acoustical treatment. 

termined by the use of the "synthetic syllable" just described. Be- 
cause of the multiplicity of the observations it is sufficient to record 
the deflections of the volume indicator on the output of the receiving 
amplifier when the syllable is projected by the theater loud speakers. 
In this way the making of many oscillograms is avoided, thereby in- 
creasing the speed of this test. 

The room noise level in most theaters has been found to be so high 
that it offers a serious handicap in making reverberation measure- 
ments. Before making such measurements the noise level is deter- 
mined so that the signal can be made sufficiently loud. The re- 
ceiving amplifier gain is then adjusted accordingly. 



FIG. 10. 

Traces of speech obtained from microphones at two different posi- 
tions in the theater after acoustical treatment. 

FIG. 11. 

Traces obtained for a dynamic speaker in a theater showing phase 
distortion and transients. 



[J. S. M. P. E. 

FIG. 12. Traces obtained for same conditions as those in Fig. 11 but out- 
of-doors instead of indoors. 

FIG. 13. Traces showing freedom from distortion of theater power amplifier. 



An excellent indication of the over-all distortion of speech which 
comes from the loud speakers of the permanent theater equipment 
can be obtained by making an oscillogram with two traces as shown 
in Fig. 9. The lower trace represents the speech which is picked up by 
a microphone MI placed about four feet in front of the speakers. The 
upper trace represents the same speech as picked up by the micro- 
phone Mz at the center of the orchestra. MI, then, is the sound as it 
is projected from the speakers while M z is the sound received by the 
listeners. The distortion at M% is so great that the syllables are barely 
discernible. After acoustically treating the theater the experiment 
was duplicated in every detail with the results shown in Fig. 10. 
The improvement is evident. The individual syllables are easily 
identified in the upper trace. It should be observed that all these 
tests were made without the presence of an audience. Proper allow- 
ance must be made for the acoustic absorption which would be due to 
the audience. 


During the routine testing of every part of the apparatus it was 
discovered that loud speakers used as a part of theater equipment are 
responsible for a large amount of distortion. When a known electrical 
wave is put into the speakers the acoustical wave projected should 
be a faithful copy. In Fig. 11 are shown the results of such a test 
on theater electro-dynamic cone speakers in a room with walls and 
ceiling covered with rock- wool one inch thick. The same experiment 
repeated out-of-doors gave the results shown in Fig. 12. Phase dis- 
tortion as well as transients are in evidence. The results of the tests 
of the electro-acoustical units are in sharp contrast to the result ob- 
tained from a similar test of a theater power amplifier. In Fig. 13 
are shown traces of the electrical wave put into the amplifier and the 
electrical wave delivered. No distortion is evident on this oscillo- 
gram. . 

Although the acoustic truck has been designed for theater work, 
any auditorium can be tested which can provide the a-c power-supply. 
Extensive experimental data on various acoustic materials have 
already been obtained by means of this apparatus in connection with 
a /sound chamber. After a material has proved its merits in the test 
chamber it can then be installed in the theater where it is again tested 
under actual operating conditions. 



MR. WEINBERGER : Has a means been found for determining the effect of the 
audience on the acoustical performance and of the scattering of the sound by the 
audience? Also, has any study been made of the effect of radiating sound from 
the horns in various directions on the reverberation produced in the theater? To 
what extent would this influence the oscillograms? By what means do you locate 
or identify the various surfaces which cause the reflections shown on the oscillo- 
grams and what is the correlation between these surfaces and the oscillographic 

MR. SCHLENKER: I have not studied the effect of the audience on the acous- 
tical performance because of the difficulty of performing experiments with audi- 
ences. Perhaps later on we can go into these problems. However, there is no 
doubt that selective reflection occurs when an audience is present. 

MR. WEINBERGER: The reverberation certainly will be influenced by the di- 
rection in which the sound is projected; have you studied this? The acoustical 
performance is greatly affected by audience reflections and I believe that these 
reflections contribute to a great extent toward the final result. 

MR. SCHLENKER: All our work has been done in empty houses. The presence 
of the audience affects the local reverberation period not so much over the 60 db. 
range as it does over the first 10 or 15 db. Over the latter range, the presence of 
the audience or of an absorbing surface has a marked effect on the decay of sound. 
We have not gone into the study in detail, and I am not able to answer your ques- 
tion fully. 

MR. EYRING: In how many theaters have you made measurements of this 
kind? How do the measured values agree with the values calculated by the rever- 
beration formula using accepted absorption coefficients. 

MR. SCHLENKER: Measurements were conducted in ten theaters. The work 
is just commencing, and it has been difficult to obtain adequate equipment. There 
is no close correlation between the calculated and the measured values because my 
measurements of reverberation are taken over a 20 db. range. This is necessary 
because of the high noise level which exists in most theaters. The loud speakers 
available will not permit more than a 30 db. increase above the noise level. How- 
ever, the decay over the first 20 db. is the more important. Further decay is 
masked by the noise in the room. 

MR. Ross: Was any attempt made to determine the particular surfaces of 
the auditorium which caused the reverberation? Since the speed of the moving 
film in the oscillograph is known, as well as the speed of propagation of sound, this 
should be possible. If, during a certain time-interval the sound wave travels a 
distance of 36 feet, it is clear that the disturbing surface must be 18 feet from the 
loud speaker. Upon locating the surface in this manner, it could be treated 
without going to the expense of treating the whole auditorium. 

MR. SCHLENKER: Knowing the time-interval and the floor plan of the theater, 
I have been able to calculate the most probable location of offending surfaces as 
close to the speaker as 6 inches. 



Summary. An illustrated description is given of some new input equipment 
for sound recording. This equipment provides for mixing the audio outputs 
of four or eight microphones into the recording amplifier, which has two output 
channels. Some of the interesting features of this equipment are: (a) Constant 
impedance mixing, providing constant load on each microphone amplifier for all 
combinations of volume control settings, thus giving unchanging fidelity and a con- 
stant output level from each microphone channel for all combinations of volume control 
settings in the other channels: (&) Filter for eliminating low rumbles, caused by 
room vibrations, wind disturbances, etc., can be switched "on" or "off" at the mixer. 
This filter does not affect the fidelity above 100 cycles, (c) Recording amplifier, 
having two output channels, supplying two loads with no interaction between them. 
Each channel has a convenient switching arrangement for changing the output trans- 
former ratio, making possible the operation of one, two, or three 500 ohm loads in 
parallel, (d) Each unit of the equipment is designed to mount on a standard relay 
rack or in an individual box equipped with handles for carrying. 

From the experience gained in the design of the two previous types 
of photophone recording equipment and from new operating and de- 
sign requirements obtained through contact with the West Coast 
Studios, general requirements for this new recording equipment have 
been formulated. The usual set-up for recording requires from one 
to four microphones. In special cases where large symphony or- 
chestras or other organizations of similar magnitude are to be re- 
corded, more than four microphones may be required. The equip- 
ment as a whole must be easily portable, so that the studios which use 
it do not require a permanent set-up of amplifiers with radiating lines 
to the several pick-up points. This portability is a distinct advantage, 
since it allows the maximum efficient use of the equipment. The pro- 
cedure for operating this equipment must be as simple as possible, so 
that the operators can focus all of their attention upon the scene, 
which is being recorded. 

The complete control of the equipment must be in the hands of 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** RCA Victor Company, Inc., Camden, N. J. 



W. P. BUTTON AND S. READ, JR. [j. s. M. P. E. 

one man, usually the chief recordist, who presides at the mixer. The 
controls on the equipment must be so adjusted with respect to each 
other, that, once the level is established, the chief recordist can con- 
veniently control the over-all output. In the particular arrangement 
which is now being used by some of the RCA Photophone licensees, 
a mixer booth, which includes space for the chief recordist, mixer 
panels, microphone control panels, power supply to the microphone 
and monitoring speaker, is usualy located directly on the stage. 
The amplifier and film recorder are usually housed in a separate booth 
somewhat off the stage. Each unit of the equipment must be capable 

!~) Gp! $ 5 

A A A A 6 6 6 



OKPflf': 'jtrcovZcir \ \MONITOR\^ 



FIG. 1. Block diagram recording equipment for four and eight microphones. 

of operating by itself or in any arrangement of similar equipment. 
In addition to its use in the portable form, this equipment must also 
be suitable for mounting on a standard relay rack where this is de- 


Using the above requirements as a foundation, this new equipment 
provides for the following features: 

For the set-up where one to four microphones are required, a four- 
microphone mixer has been designed. This is used in conjunction 
with a control panel for supplying power to the four microphones and 
connecting the audio output of the microphones to the mixer panel. 
From the mixer panel, the audio signal is connected to the input of 



the recording amplifier, which has two similar output stages. For 
the set-up where more than four microphones are required, two of the 
four-microphone mixers and two of the four-microphone control 
panels are supplied. An additional unit is furnished for combining 
the audio outputs of the two four-microphone mixers. This unit is 
known as the over-all mixer. The recording amplifier remains the 
same. A block diagram shown in Fig. 1 gives a graphic picture of 
these two set-ups. 

Each unit of this equipment is mounted in a carrying case which is 
provided with the necessary handles for carrying. These units are 
of such size and weight that they can be easily carried by one man, 
with the exception of the amplifier, which weighs approximately 65 

FIG. 2. Schematic diagram four-microphone mixer (PB-11). 


Ibs. Each unit of this equipment has the minimum number of con- 
trols without sacrificing any of the desirable technical and operational 
features. Each unit can be operated by itself, with the remaining 
parts of the equipment or with equipment of a similar type. Those 
units which require power for the "A" and "B" circuits have a 
switch, fuse, and a signal light, built in as part of the unit. For the 
case where it is desired to mount these units on a relay rack, shields 
and terminals for wiring connections are provided. A more detailed 
description of the several "units is given below. 


The four-microphone mixer provides for the following: 

(1) Control of the individual audio outputs of four-condenser 


W. P. BUTTON AND S. READ, JR. [j. s. M. p. E. 

microphone amplifiers, each having an output transformer designed 
to work into a 250 ohm line. 

(2) Control of the combined output of the four-microphone 

(3) Switching means for connecting or disconnecting any one of 
the four-microphone circuits at will. 

(4) An attenuating network to cut off frequencies below 100 

Referring to Fig. 2, the audio inputs to this panel are connected 
through an eight-conductor cable, plug, and receptacle from the four- 
microphone control panel, or directly to the respective input ter- 

ffft tOff 1000 2000 4000 6000 IO,000 

FIG. 3. Frequency characteristic four-microphone mixer (PB-11). 

minals. The audio output of the panel is connected to terminals and 
binding posts. Listening jacks are provided for each of the four in- 
put circuits and also the output circuit, for headphone monitoring or 
trouble shooting. The double-pole, double-throw "on"-' 'off" 
switches for each microphone circuit operate as follows: 

In the "on" position they connect the input from the receptacle, 
input terminals and listening jacks direct to the corresponding "T" 
pad circuit. In the "off" position they disconnect the input recep- 
tacle, input terminals and listening jacks from the "T"-pad circuit, 
ground one side of the input line, and connect another resistor to the 
"T"-pad circuit to simulate the load of the microphone amplifier. 
The "T"-pads used in this mixer are of the constant impedance, con- 


tinuously variable type. Two arms of the pads have straight re- 
sistance variation and the third arm is tapered for proper loading. 
The over-all attenuation of the mixer is twenty decibels, the lower 
range having straight line variation. 

The connections and loading are so arranged that the load on each 
microphone amplifier is constant for all settings of the volume control. 
This connection insures unchanging fidelity from each microphone 
amplifier and that the output level from each microphone channel 
is not affected by the volume control settings in the other channels. 
The calculations of the mixing circuits, particularly the proper loading 

FIG. 4. Four-microphone mixer rear view showing unit removed from 

box (PB-11). 

for constant impedance mixing, presented an interesting problem. 
The equations used in these calculations are covered in the "Appen- 

The filter for attenuation of frequencies below 100 cycles can be 
switched "on" or "off" at will. It consists of two sections and gives 
a curve as shown in Fig. 3. 

Curve 1 is the normal frequency characteristic of the recording 
amplifier. Curve 2 is the frequency characteristic of the mixer and 
recording amplifier, as connected for normal operation, with 1.14 
volts across the filter. Curve 3 is the same with 0.0018 volt across 
the filter. These two voltages are probably the maximum and mini- 


W. P. BUTTON AND S. READ, JR. [j. s. M. p. E. 

mum voltages which will be encountered and therefore represent the 
limits of the filter cut-off under actual operating conditions. Such a 
characteristic tends to reduce low frequency disturbances caused by 
room vibrations, wind currents, etc. 

The filter switch operates as follows: In the "on" position, it 
connects the two capacitors in series with the line, and the reactor 
across the line, to the over-all volume control. In the "off" position, 
it short-circuits the capacitors and disconnects the reactor. A rear 

FIG. 5. Schematic diagram four-microphone control panel (PB-12). 

view of the four-microphone mixer, removed from the box, is shown 
in Fig. 4. The identities of the several parts are as indicated. 


The four-microphone control panel provides for the following: 

(1) Control of the power-supply to four-condenser microphone 
amplifiers with suitable protection for "A" and "B" supply. 



(2) Separation of the audio outputs of the four-condenser micro- 
phone amplifiers and transfer to the four-microphone mixer. 

Referring to Fig. 5, the power input to the panel is connected 
through a five-conductor male plug, a power-control switch and two 
fuses for protection of the "A" and "B" supply. The signal light 
indicates when the filament voltage is "on." The audio and power 
inputs to the microphone amplifiers are connected through four five- 



" mm^ /? 
. (& 




FIG. 6. Four-microphone control panel bottom view 
showing unit removed from box (PB-12). 

conductor, female receptacles. The audio output of each micro- 
phone amplifier is connected to a pair of contacts in the eight-con- 
ductor receptacle, and then by cable to the four-microphone mixer. 
A bottom view of the four-microphone control panel removed from 
the box is shown in Fig. 6. The identities of the several parts are as 


The over-all mixer provides for the following: 


W. P. BUTTON AND S. READ, JR. [j. S. M. P. E. 

(1) Connection of the audio outputs of two of the four-microphone 
mixers into one over-all control. 

(2) Connection of the combined output to the recording amplifier. 

Referring to Fig. 7 the audio inputs to this panel are connected 
through binding posts or terminals from the two four-microphone 
mixers. The audio output is also connected to binding posts and ter- 
minals. Listening jacks are provided in each input circuit and in 
the output circuit for head-phone monitoring or trouble shooting. 
The double-pole, double-throw "on"-' 'off" switches for each input 
circuit operate as follows: 

In the "on" position, they connect the input from the binding posts, 
input terminals and the listening jacks, direct to the "T"-pad circuit. 
In the "off" position they disconnect the binding posts, input ter- 


fa r 




FIG. 7. Schematic diagram over-all mixer (PB-13). 

minals and listening jacks from the "T"-pad circuit, ground one 
side of the input line, and connect another resistor to the "T"-pad 
circuit to simulate the load of the four-microphone mixer. The same 
general equations as derived for the mixing circuit of the four-micro- 
phone mixer are used for this panel. These equations are covered 
in the "appendix." A rear view of the over-all mixer removed from 
the box is shown in Fig. 8. The identities of the several parts are 
as indicated. 


The recording amplifier provides for the following: 

(1) Sufficient amplification to supply the recorder with the proper 
audio level under the most adverse conditions to be encountered in 
the usual stage set-up. 


(2) Sufficient undistorted audio power for the operation of two 
recorders similar to the type PR-4 Recorder described by Kellogg. 1 

(3) A frequency response of plus or minus one decibel, from the 
1000 cycle value, over a range from 100 to 10,000 cycles. 

(4) Sufficient controls, so designed that the audio output can be 
controlled from the mixers for ordinary operating conditions, without 
touching the amplifier. 

The recording amplifier contains a four-stage voltage amplifier, 
utilizing UX-864 Radiotrons, connected to the paralleled input of two 
similar push-pull power stages, utilizing UX-171-A Radiotrons. It 
has an over-all amplification of approximately 85 db. and the maxi- 
mum undistorted power output from each of its output stages is 800 

" : 

FIG. 8. Over-all mixer rear view showing unit removed from box (PB-13). 

milliwatts. Two volume controls are provided ; the main one is con- 
nected across the secondary of the input transformer and has twenty 
steps with 2-db. variation between steps; the auxiliary volume 
control is connected in the grid circuit of the second voltage amplifier 
and has three steps with 20-db. variation between steps. The only 
other controls on the face of the panel are the power control switch 
and the rotary switch for transfer of the meter from one circuit to 
the other. 

Referring to Fig. 9, the audio input to this panel is connected 
through binding posts or terminals from either the four-microphone 
mixer or the over-all mixer, depending upon the particular set-up. 
The audio output of each power stage is also connected to binding 
posts and terminals. Listening jacks are provided in the input cir- 


W. P. DUTTON AND S. READ, JR. [J. S. M. P. E. 

cuit and also in each output circuit, for head-phone monitoring or 
trouble shooting. The power input to the panel is connected through 
a five-conductor female receptacle or terminals, to a power control 
switch and fuses for protection of the "A" and "B" supply. The 

FIG. 9. Schematic diagram recording amplifier (PA-47). 

signal light indicates when the filament voltage is "on." Metering 
of the bias voltage on the UX-171-A stages, filament voltage on the 
UX-864 and the UX-171-A power stages, and plate currents of the 
power stages are observed by means of a d-c milliammeter in connec- 
tion with suitable series resistors, shunts, and a rotary switch. 

40 60 100 ZOO 400 6OO WOO ZOOO 40OO 60OO JOOOO 

FIG. 10. Frequency characteristic recording amplifier (PA-47). 

The input transformer is designed to work from a 500 ohm line, 
has a balanced primary with mid-tap, and a static shield between the 
primary and secondary windings. The main volume control has a 
maximum resistance of 100,000 ohms. There is a variation of 2db. 



between steps with an "off" position. The filaments of the four UX- 
864 Radiotrons are connected in series with a filament reactor in the 
positive side and a series resistor in the negative side. This connec- 
tion provides a bias potential which is successively more negative 
for each stage. The filaments of the UX-171-A power stages are 
connected in parallel with a filament reactor in the positive side. 
The UX-864 plate circuits consist of a plate reactor which is common 
to the four tubes, individual series resistors with by-pass capacitors 

FIG. 11. 

Recording amplifier rear view showing unit removed 
from box (PA-47). 

for filtering, and the plate resistor. Coupling condensers between 
stages are of such value that the required fidelity curve can be ob- 

Each UX-171-A plate circuit consists of a plate choke, primary of 
the push-pull output transformer, and plate current metering shunt. 
The grids of each push-pull output stage are supplied from the plate 
circuit of the last voltage amplifier stage through a coupling capacitor 
and auto-transformer. The four grids of the two stages are connected 


W. P. BUTTON AND S. READ, JR. [j. S. M. p. E. 

in push-pull, parallel across the auto- transformer. The output trans- 
former of each stage has a balanced secondary with mid-tap. Three 
taps either side of this mid-tap are provided for working into a 500 
ohm, 250 ohm, or 167 ohm line. The power required for operation 
of this amplifier is 1.25 amperes at 6 to 8 volts d-c for filament supply 
and 0.065 ampere at 250 volts d-c for plate supply. 

Some of the design features which lessen external disturbances 

and contribute to the stable and con- 
venient operation of this amplifier are: 

(1) Use of the UX-864 non-micro- 
phonic Radiotron. This tube was 
originally developed for use in the 
RCA condenser microphone where a 
non-microphonic tube is absolutely 
required for quiet operation. 

(2) The two filament circuits each 
have a filter reactor. 

(3) Plate battery supply to the 
amplifier is by-passed by condensers. 

(4) Each stage of the voltage 
amplifier has a resistance-capacity 
filter in its plate circuit. 

(5) Each output stage has a 
convenient switching arrangement 
for changing the output transformer 
ratio so as to work into a 500 ohm, 
250 ohm, or 167 ohm line. 

A fidelity curve of this amplifier is shown in Fig. 10. A rear view 
of the recording amplifier removed from the box is shown in Fig. 11. 
The identities of the several parts are as indicated. 

Referring again to Fig. 1, a view of the equipment for eight micro- 
phones mounted in a standard relay rack, is shown in Fig. 12. The 
several units in each of these photographs may be identified by their 
type numbers. 




The output of a microphone amplifier can be controlled (decreased 
or attenuated) keeping the load on the amplifier and the resistance 

FIG. 12. Recording equipment 
for microphones. 

March, 1931] 



looking from the other side of the controlling device toward the ampli- 
fier constant if a "T" resistance section is used. Referring to Fig. 
13 (Part 1), the resistance R of such a section is the resistance looking 
into either end when the other end is loaded with a resistance R. If 
the desired ratio of input to output voltage is represented by K and 
the input and load resistances by R the value of RI, R%, and Rs are 





FIG. 13. 


Formulas for constant impedance mixing system. 


Referring to Fig. 13 (Part 2), which represents a general mixing sys- 

Let N = No. of amplifiers, whose outputs are to be combined. 

A = Resistance of "T" section in the microphone amplifier circuit. 

W = Resistance of "T" section used for overall control. 

X = Shunting resistance across the output of the "T" section used in the 

microphone amplifier circuit. 
Y = Resistance of A and X in parallel. 

The resistance Y will remain constant for all attenuations of micro- 
phone amplifier outputs (as explained under "T"-pad discussion 

328 W. P. BUTTON AND S. READ, JR. [j. s. M. p. E. 

above). Therefore, varying the attenuation of one of the inputs 
will not affect the attenuation of any of the other outputs. The 
load on each input circuit will not change if its "T" pad is properly 
loaded by the resistance X in parallel with (N 1) Y + W 

X((N - 

X + ((N - 1) Y + W] 

v = AX 

Combining (3) and (4) 

X = 2[W + A(N -2)] [ NA + V(NA+2W)*-8AW]. (5) 

If the resistance M looking from the combined output circuit does 
not have to remain constant, values of N, A, and W can be substituted 
into equation (5) and the value of the loading resistor X determined. 
If several of the combined outputs are to be combined into one chan- 
nel it is obvious that M must equal W and remain constant. This 
imposes the condition that: 

W = NY (6) 

Solving, 3, 4, and 5 

W and N known 


A and N known 

It should be noted that the last-imposed condition makes it pos- 
sible to choose only two of the variables in the system. 

As was previously mentioned, it was decided to design a four-micro- 
phone mixer and another over-all mixer for combining the outputs of 
two four-microphone mixers. 


It was desirable to have the input to the recording amplifier equal 
to 500 ohms so for four microphones W = 500 ohms and JV = 4. 


From equation 7 and 8, A = 219 ohms, and X = 292 ohms. 

The plate impedance (referred to transformer secondary) of the 
output tube in the microphone amplifier is 125 ohms; therefore 
a series resistance of 219 125 or 94 ohms must be added, so as to 
make the input resistance to the pad equal to A. This means the 
microphone amplifier has a constant load of 313 ohms. (See Fig. 2.) 


Since M does not have to equal W, equation 5 can be used to solve 
for X. Thus, N = 2 and A = W = 500 ohms; then X = 1212 
ohms. (See Fig. 7.) 


1 KELLOGG, E. W.: "A New Recorder for Variable Area Recording," JOUR. 
Soc. MOT. PICT. Eng., XV (November, 1930), No. 5, p. 653. 



Summary. An analysis is made of the factors which affect the choice of ma- 
terials to be used for the construction of various types of processing apparatus. Three 
general classes of material are considered, namely: (1) metals, (2) coated metals, and 
(5) non-metallic materials. In addition to the direct action of solutions on metals, 
the possibility of electrolytic corrosion effects must be recognized. The results of an 
exhaustive series of tests on the effect of photographic solutions on single metals and 
metallic couples are summarized, including the effect of the materials on the solutions. 

Practical recommendations are given regarding materials suitable for the construc- 
tion of apparatus such as processing machines. 

When selecting a material for the construction of processing ap- 
paratus, several factors should be considered, namely: 

(1) The resistivity of the material to the most corrosive liquid 
with which it will come in contact. For example, a galvanized tank, 
while fairly satisfactory for washing purposes, is very rapidly cor- 
roded by fixing baths. 

(2) The effect of the material on the photographic properties of 
the solution. For instance, a developer solution in a brass tank may 
appear visibly unchanged, but on testing, it may fog emulsions 
badly, due to the presence of copper salts dissolved from the 

(3) The time during which the solution will be in contact with 
the material. If a developer is stored in a japanned tank, the japan 
will ultimately soften and peel off. 

(4) The cost of the material. 

(5) The adaptability of the material for construction purposes. 
Glass, for example, is entirely unsuitable for large tanks because of 
its fragility, and the difficulty of annealing such tanks. 

There are three general classes of materials suitable for the con- 
struction of processing apparatus : metallic materials, coated metals, 

* Received by the Editor, February 2, 1931. 
** Kodak Research Laboratories, Rochester, N. Y. 


and non-metallic materials. These may be sub-classified as follows: 

A. Metallic materials: Unplated and plated metals; alloys. 

B. Coated metals: Enameled steel, asphalt-coated metals, and 
lacquered metals. 

C. Non-metallic materials: Enameled steel, glass, impregnated 
fibrous materials, wood, paraffined wood, porcelain and glazed 
earthenware, rubber, rubber composition, nitro-cellulose mate- 
rials, slate and Alberene stone. 


No metal or alloy has yet been found which will resist corrosion in 
all photographic solutions, and it is therefore necessary to restrict 
their use to specific purposes. Metallic materials possess certain 
very desirable properties, however, such as ductility, non-fragility, 
and general workability. 

In considering the suitability of a particular metal for construction 
purposes, it is very important to know whether the article will be 
built of a single metal or of two or more metals. In the former case, 
only the corrosive effect of the solution itself need be considered, 
whereas in the latter case, an electrical current flows between the two 
different metals and its effect must be considered in addition to the 
chemical action. 

In testing the resistivity of various metallic materials to chemical 
action, it is necessary to observe the effects obtained under two sets of 
conditions: (1) those in which only a single metal or alloy is involved, 
and (2) those in which two or more metals or alloys are in contact with 
each other and also with the photographic solutions. 

The Resistivity of Single Metals in Photographic Solutions. An 
extended series of tests was carried out to determine the resistivity 
of a large number of metals and alloys to common photographic 
solutions. The experimental details of the tests made on most of the 
materials given in the following list, are recorded in papers by two of 
the present authors. 

Metals Aluminum, Iron, Lead, Nickel, Tin, Zinc. 

Plated Metals Galvanized Iron; Tinned Iron, Lead-coated Iron; 
Aluminum-coated Iron; Chromium, Silver, and Cadmium-plated 

Alloys Allegheny Metal (chromium-nickel-steel), Aterite No. 
136 (copper-zinc-nickel), Brass, Duriron, Monel, Niaco (nickel alloy), 
Nickel Silver (copper, zinc, nickel, iron), Nicolene (nickel-copper), 


Phosphor Bronze (copper-tin-phosphorus), Solder (both high and low 
tin content), Rezistal Steel (chromium steel), Type Metal (lead-tin- 
antimony), Duralumin (aluminum-magnesium-copper), Corronil 
(nickel alloy), Nichrome (nickel-chromium), and various Stainless 

The Resistivity of Two or More Metals in Metallic Contact toward 
Photographic Solutions. When two different metals are placed in 
contact and immersed in a solution, an electrolytic battery is formed 
which causes more or less rapid disintegration of one of the metals. 
This electrical action may occur in several ways: with plated metals, 
when some of the plating wears off; with soldered metals, between 
the solder and the metal; and with alloys, between the tiny crystals 
of the various metals which compose the alloy. 

In making metal containers for photographic solutions, it is often 
necessary to use a second metal or alloy in the form of solder, to 
render joints or seams free from leaks. Also, in the construction of 
pipe lines for transporting solutions, it is frequently not possible to 
use faucets or fittings of the same material as the pipe line. A con- 
crete example of the trouble which may arise from the metallic con- 
tact in a solution is as follows: 

In the course of a series of tests on metal tanks of a copper-nickel 
alloy, soldered on the inside with a lead-tin solder, it was observed 
that if a developing solution remained in the tank for a short time 
the developer gave very bad fog. The solder with which the seams 
of the tank were soldered appeared to be slightly etched, and the 
original luster of the metal had disappeared, being replaced by a dark, 
grainy deposit. The alloy itself was unaffected as far as could be 
detected from its physical appearance. A series of tests definitely 
proved that the excessive fog was a result of the tin constituent of 
the solder passing into solution, due to the flow of an electric current 
through the solder, the solution, and the alloy. 

Corrosion was also observed due to the same cause when a tank 
made from this alloy and soldered on the inside was used as a con- 
tainer for an acid fixing bath, except that the alloy was corroded in- 
stead of the solder. When the joints were soldered on the outside, no 
developer fog was produced and corrosion was considerably less. 

An extended study of this aspect of corrosion was made and the 
results are given in the two papers to which reference was made 

Only the practical application of the results of tests on the various 


metals will be considered in this article; the orginal papers should be 
consulted for more detailed information. 1 ' 2 ' 3 

Practical Value of Metal Materials, Lead and nickel were the 
only metals tested which appeared to be of any special importance 
for use with processing solutions although iron is of value for particu- 
lar purposes. Lead, nickel, and iron (black or ungalvanized) tanks 
or piping can be satisfactorily used for most developing solutions al- 
though lead is attacked by strongly alkaline developers. Tanks 
lined with lead or nickel can be used for fixing solutions but they are 
slowly attacked, become coated with silver, and must eventually be 

Practical Value of Plated Metals. Galvanized iron has long been 
used for the manufacture of washing tanks although it is not entirely 
suitable for this purpose. Vessels made of this material must not 
be used for mixing developers which contain sodium bisulfite, because 
the bisulfite attacks the zinc coating, forming sodium hydrosulfite 
which causes fog. 4 

Nickel-plated brass is satisfactory for small developing tanks which 
are used intermittently. Metals plated with silver, either by deposi- 
tion from an exhausted fixing bath, or by electroplating, are more 
resistant to developing solutions according to the homogeneity of the 
silver coating, but their resistance toward fixing baths is only slightly 
greater than that of the unplated metals. Aluminum- and cadmium- 
coated metals do not satisfactorily resist photographic solutions. 
Chromium-plated metals would probably be satisfactory if it were 
possible to secure a continuous non-porous coating over the base 
metal, but no such coatings are available to date. Lead-coated iron 
can be used for developing and washing tanks if the iron base-metal 
is not exposed, but is not very satisfactory. 

Plated metals and alloys are always open to the objection that as 
soon as some of the plating wears off, exposing the base-metal under- 
neath, electrolytic corrosion sets in, and disintegration takes place 

Practical Value of Alloys. Of the numerous known alloys, Monel 
metal has been most extensively used although it is less satisfactory 
than certain types of stainless steel such as Allegheny metal. Monel 
metal as well as plain nickel and Corronil metals gives similar results 
to Monel metal. Monel metal is attacked and coated with silver 
when stored in used fixing solutions. 

Allegheny metal is resistant to both developing and fixing solutions, 

334 CRABTREE, MATTHEWS, AND Ross [j. S. M. p. E. 

and has the least tendency of the commercial alloys to accumulate 
a deposit of silver in a used fixing bath. Also, very little corrosion 
occurs in a fixing bath if the alloy is completely immersed but if 
partially exposed to the air, corrosion pits form somewhat readily 
around the air line. However, it is the most satisfactory commer- 
cially available alloy. 

Alloys often are more resistant to the action of certain acids and 
alkalis than the metals of which they are composed, as, for example, 
Duralumin, whose tensile strength and resistance to acids are far above 
that of aluminum. Some samples of this alloy looked rather promis- 
ing for use with photographic solutions while others were not satis- 
factory and for this reason the material cannot be unqualifiedly recom- 


Enameled Steel. Enameled steel is extensively used for small tanks 
and has proved fairly satisfactory. When the undercoating of steel 
is laid bare by the chipping away of the relatively brittle vitreous 
enamel, it corrodes very rapidly, and the vessel is rendered useless. 
Smooth, hard enamel coatings are resistant to weak acids but with de- 
velopers and alkaline solutions the surface becomes etched, making 
it difficult to clean. Dye solutions permanently discolor such rough- 
ened surfaces of enamel. 

Lacquered Metals. A satisfactory photographic lacquer consists of 
asphalt paint or a mixture of asphalt paint with rubber cement, the 
latter serving to overcome the slight brittleness of the asphalt coat- 
ing. Baked japan is very satisfactory, but none of these materials 
will resist developing solutions containing a high percentage of alkali. 
Freshly applied asphalt paint will often produce a scum on the de- 
veloper surface. 


Several satisfactory materials for use in handling photographic 
solutions on a large scale are to be found in the non-metallic group. 

Glass. Glass apparatus, well annealed, free from ribs, and with 
the corners of tanks rounded off, is quite satisfactory and is one of the 
most resistant materials available. For the storage of strong alkalis, 
special resistant glass should be used. Owing to its fragility, however, 
glass is not suitable for large tanks. 

Impregnated Fibrous Materials. Tanks prepared with fibrous ma- 
terials impregnated with varnish or lacquer develop cracks with use, 



thus permitting access of the solutions to the under layers. Such 
tanks are entirely unsatisfactory for use with solutions containing 
strong alkalis, or with fixing baths, because these solutions disinte- 
grate the fibrous materials through crystallization as explained later 
under "Porcelain and Glazed Earthenware." 

Containers made from most laminated phenolic condensation 
products can be used with photographic solutions, with the exception 
of strong oxidizing solutions. Some samples of these materials have 
been found to swell and warp out of shape when used with strongly 
alkaline solutions. 

Wood. Wood is fairly satisfactory for developing, fixing, and wash- 
ing purposes and is cheaper than any other available material. It 
has the disadvantage that, unless strongly braced, it has a tendency 
to warp out of shape. In many localities fungus growths accumulate 
on the outside of the washing tanks which must be removed fre- 
quently, while the inside of wash tanks often becomes coated with a 
layer of slime which necessitates frequent cleaning. Wooden con- 
tainers also become permanently discolored if they are used for dye 
solutions. The most satisfactory varieties of wood for the construc- 
tion of tanks are cypress, spruce, redwood, maple, and teak. 

Paraffined Wood. Although certain woods such as cypress and 
teak are frequently used for the construction of containers for photo- 
graphic solutions, paraffin-impregnated wood is much more satis- 
factory. It also possesses the additional advantage that it does not 
tend to accumulate slimy layers as rapidly as unwaxed wood. The 
chief disadvantage of paraffined wood is that it is too heavy for the 
construction of large equipment which is to be handled manually. 
Methods of impregnating wood with paraffin have been investigated 
by Eberlin and Burgess, 5 who found that the best results were ob- 
tained with cypress and spruce by soaking in water for twelve hours, 
and then immersing in molten paraffin was for two hours at about 
257F. (125C.). If the wood becomes overloaded with paraffin, it 
loses its resiliency and breaks easily. A shorter time of treatment or 
a lower temperature should then be used so that less paraffin becomes 
absorbed by the wood. 

The soaking serves to swell the wood and in the hot paraffin bath 
the water in the pores is replaced by paraffin. The wood should be 
wiped thoroughly with a cloth on removing from the paraffin bath 
so as to remove the excess wax. Water-tight joints with paraffined 
wood are best made by grooving the pieces of wood to be joined 


together, as for a T-joint, and inserting tightly a small piece of 
unparaffined wood in the groove. When placed in water the un- 
treated strip swells and completely caulks the seam. 

Porcelain and Glazed Earthenware. Porcelain, glazed biscuit-ware, 
and tile material are usually unsatisfactory because the glaze invari- 
ably cracks, causing minute fissures into which the solution pene- 
trates and crystallizes. The crystals then grow and cause the biscuit- 
ware to disintegrate, incidentally causing the glaze to chip. Tanks 
of high-grade, dark-brown earthenware, glazed on both sides are 
especially recommended for storing ordinary developing and hypo 
solutions, but should not be used with strong alkalis. 

Rubber, Rubber Composition, Nitrocellulose, and Asphaltum Ma- 
terials. Pure hard rubber will withstand practically all photographic 
solutions at normal temperatures. Some so-called hard rubber tanks 
are made from a mixture of asphalt or rubber composition with an 
excess of mineral filler. Such tanks are somewhat brittle, warp 
under heat, and when used as containers for solutions disintegrate in 
the same manner as porous earthenware. Smooth surfaces reduce th : 
tendency to etching since less strain is exerted on the walls during the 
crystallization process. 

Rubber sheeting and rubberized cloth are often used for coating 
the inside of wooden trays and troughs, and are very satisfactory. 
Cheap rubber sheeting or tubing often contains an excess of free sulfur 
which reacts with photographic developers and causes chemical 
fog. 6 Pure gum-rubber materials are quite satisfactory. 

A tarry material called "Oxygenated Asphalt" used for sealing 
storage batteries and supplied by the Standard Oil Company, has 
been found to be a satisfactory protective coating for use with all 
kinds of photographic solutions. This material is applied while 
hot as a thick coating over the metal or wood, and if a smooth surface 
is desired the coating can be smoothed out by the use of a blow-torch. 
Nitrocellulose lacquer (E. K. Lacquer No. 5119) is useful for coating 
wooden articles such as racks for handling motion-picture film, al- 
though several coatings are usually necessary, either by brushing, 
spraying, or dipping. Small apparatus constructed of nitrocellulose 
sheeting is satisfactory for use with almost every type of aqueous 
solution. 7 Wooden tanks lined with this material have also proved 

Slate and Alberene Stone. These materials are very suitable for 
constructing large tanks for containing developing solutions. For 


fixing solutions, Alberene Stone (a gray, finely crystalline variety of 
soapstone) is entirely satisfactory, but slate is not recommended as 
it often splits along planes of cleavage as a result of crystallization. 
Some varieties of soapstone are not resistant to fixing baths, and tend 
to disintegrate where the sodium thiosulfate crystallizes out. 

A satisfactory cement for joining large pieces of soapstone, as in 
constructing a tank, can be prepared from 1 part whiting and 2 parts 
litharge, thoroughly mixed and made into a putty with boiled linseed 
oil. A mixture of litharge and glycerine is recommended for cement- 
ing small fittings into the tanks. 


Materials suitable for constructing various types of photographic 
apparatus are as follows: 

Small Apparatus. Allegheny metal is one of the most satisfactory 
materials known. Nickel, Monel metal, Mond, and Corronil metal 
are suitable for use in developing solutions. 

Small Tanks. Since these containers are generally used for a 
variety of purposes, they should be resistant to most photographic 
solutions. Suitable materials are glass, enameled steel, hard rubber, 
teak wood, or spruce impregnated with paraffin wax, wood, or metal 
coated with "Oxygenated Asphalt," and well-glazed porcelain or 
stoneware. Allegheny metal, Monel, Mond, or Corronil metals and 
nickel with pressed seams or joints soldered on the outside are satis- 
factory for washing or developing and for fixing purposes when the 
tanks are to be used intermittently. 

Deep Tanks. Alberene stone, well-glazed stoneware, and wood 
(cypress) are suitable for developing and fixing baths. Lead-lined 
wooden tanks are fairly satisfactory for developing solutions pro- 
vided the joints are lead-burned and not soldered. Plain wooden 
tanks are satisfactory but they tend to accumulate slime. Tanks of 
paraffined wood can be used if the wood is properly joined together 
with strips of untreated wood as explained above. Tanks of Port- 
land cement have been found satisfactory for developers of low alkali 
content. Metal or wooden tanks coated with "Oxygenated Asphalt" 
are excellent providing the base-material is not exposed. 

Tubes, Sprockets, and Idlers for Motion-Picture Developing Ma- 
chines. Hard rubber, lead, Allegheny metal, and Pyrex glass have 
been found satisfactory for developing tubes. Lead gathers a deposit 


of silver from the fixing bath, and in time this tends to obstruct the 
tube. However this deposit can be removed by scraping. Brass or 
copper tubing should not be used since both materials affect de- 
velopers and are corroded by fixing baths. Idlers and sprockets 
should preferably be made of hard rubber or Allegheny metal accord- 
ing to the purpose for which they are intended. Metal tubing should 
not be soldered with solders containing tin. 

Troughs for Reel Development. Glazed stoneware and wooden 
troughs lined with sheet rubber or rubberized cloth are satisfactory 
for practically all ordinary processing solutions. Lead, Mond, 
Nickel, Allegheny metal, Monel, and Corronil metals are satisfactory 
for use with developing solutions but are slowly attacked by fixing 
solutions. For acid oxidizing solutions or strong alkalis, glazed 
stoneware troughs are recommended, but the troughs should be emp- 
tied after use. Metal troughs may be used in an emergency if the 
interior of the trough is lined with pure gum rubber sheeting or paraf- 
fined cloth. This latter lining is applied by coating the interior 
of the trough with cloth and sticking it to the metal with Cumar 
resin (medium hard grade). The cloth is then brushed over with 
molten hard paraffin wax and the surface finally smoothed oft 7 with 
a hot iron. Metal troughs may also be coated with "Oxygenated 
Asphalt" but great care should be taken to insure that the metal is 
covered completely and that the coating is free from bubbles. Ja- 
panned metal-ware is satisfactory only for intermittent use. 

Piping, Pumps, Faucets, Etc. For transporting developing solu- 
tions, hard rubber, iron (not galvanized), Duriron and Allegheny 
metal piping and pumps are satisfactory and should be used in con- 
nection with faucets of similar materials. For transporting fixing 
solutions, hard-rubber piping, valves, and pumps are recommended. 
Tinned or tin-lined copper or brass faucets or piping should be 
avoided for use with developers or fixing solutions. For conveying 
distilled water, however, pipe lines and fittings of block tin soldered 
with pure tin solder are satisfactory. Lead piping joints should be 
"wiped" or lead-burned, and not soldered. If silver-plated apparatus 
is used, the plating should be free from pinholes or scratches. 

A suitable packing for pumps consists of asbestos rope twisted 
with the aid of a little hard grease. 

Lead and hard-rubber piping needs supporting while hard rubber 
must be protected from blows or excessive pressure. 

The following table summarizes the above recommendations. 



Construction Materials for Processing Apparatus 


Storage Tanks 

Pipe Lines 


and Idlers 




Black iron (not 








Monel metal 


Soft rubber 


Monel metal 



Monel metal 

Lead-lined wood 

Glazed earthen- 


Hypo not 


Hard rubber 






Soft rubber 







Monel metal 

Monel metal 



Glazed earthen- 

ware crocks 

Hypo con- 


Hard rubber 






Soft rubber 






Monel metal 

Monel metal 










Soft rubber 

Monel metal 

Monel metal 


(1) Do not permit tin, copper, or alloys containing these metals to 
come in contact with developing solutions, especially concentrated 
developers, because more or less of the tin or copper will dissolve and 
cause either serious chemical fog or rapid oxidation of the developer. 
Do not use galvanized-iron vessels to mix developing solutions con- 
taining sodium bisulfite because sodium hydrosulfite which is a bad 
fogging agent, will be formed. Likewise, the zinc in the inner coating 
of galvanized piping will cause developer fog. 

Contact between two or more different metals or alloys exposed to 
a developer will hasten the rate of corrosion of the metals and thus 
increase the amount of fog obtained. Soldered joints are particularly 
to be avoided with developers, but if such joints are unavoidable, a 
low- tin solder or one free from tin should be used, and the joints so 
made that a minimum of solder is exposed to the solution. 

(2) For fixing, toning, and acid-oxidizing solutions, avoid metals 
whenever possible. 

(3) When choosing metal for the construction of apparatus a single 
metal should be used whenever possible, and it should be either elec- 
tro-welded or soldered from the outside to avoid electrolytic corrosion. 
Lead containers should be joined together by lead burning. 

(4) Apparatus constructed of aluminum, zinc, or galvanized iron 


should not be used with either developers or fixing baths since these 
metals react with such solutions with the formation of precipitates 
which leave a deposit on the film and often stain the gelatin. 

(5) Plated metals should be avoided whenever possible and only 
single metals or alloys used in preference, since electrolytic corrosion 
sets in as soon as a little of the plating wears off. 

(6) For fixing baths or strong saline solutions, avoid porous ma- 
terials such as incompletely-glazed earthenware, impregnated fibrous 
materials, or rubber compositions, because crystallization of the salts 
within the pores of the materials causes disintegration. 

(7) Tanks coated with lacquer or baked japan are not resistant to 
strongly alkaline developers or fixing baths of high acid concentration. 

(8) Avoid the use of cheap rubber tubing or other materials con- 
taining free sulfur or metallic sulfides in connection with developing 
solutions, because the alkali in the developer attacks these, forming 
alkaline sulfides which cause chemical fog. 


1 CRABTREE, J. I., AND MATTHEWS, G. E.: "The Resistivity of Various 
Materials toward Photographic Solutions," Ind. Eng. Chem., 15 (1923), p. 666. 

2 CRABTREE, J. I., HART, H. A., AND MATTHEWS, G. E.: The Effect of 
Electrolysis on the Rate of Corrosion of Metals in Photographic Solutions," 
Ind. Eng. Chem., 16 (1924), p 13. 

3 CRABTREE, J. I., AND MATTHEWS, G. E. : "Corrosion of Monel Metal in 
Photographic Solutions," Ind. Eng. Chem., 16 (1924), p. 671. 

4 Ross, J. F., AND CRABTREE, J. I.: "The Fogging Properties of Developing 
Solutions Stored in Contact with Various Metals and Alloys," Amer. Phot., 23 
(1929), p. 254. 

6 EBERLIN, L. W., AND BURGESS, A. M.: "Impregnating Wood with Paraffin," 
Ind. Eng. Chem., 19 (1927), p. 87. Revised, 1928. 

6 CRABTREE, J. I.: "Chemical Fog," Amer. Ann. Phot., 33 (1919), p. 20. 

7 HiCKMAN, K., AND HvNDMAN, D. E. : "Plastic Cellulose in Scientific Re- 
search," /. Frank. Inst., 207 (1929), p. 231. 



Summary. From available data on the acuity of hearing of various groups 
of people, a chart is constructed showing the estimated distribution of any large 
group according to their hearing ability. Articulation vs. loudness curves are used 
to determine the amount of aid possible for any particular degree of deafness. From 
these sources it is estimated that approximately 10 per cent of the population who 
now cannot hear sound pictures satisfactorily can, with benefit, use a theater-hearing- 
aid system which reproduces without distortion; this number is reduced corre- 
spondingly with the amount of distortion introduced. The requirements of such a 
system are outlined and the Western Electric theater-hearing-aid attachment is 
described in detail. 

During the early days of sound pictures when new converts were 
being added to the list of enthusiastic theater patrons, a small dis- 
cordant note made its appearance. This arose from a minority, who, 
knowingly or unknowingly, had defects in hearing which were suf- 
ficiently serious to prevent proper reception of this new form of 
entertainment. The various societies for the hard-of-hearing, by 
circularizing the producing companies and by means of publicity, 
sought to stem the tide which was eliminating the silent pictures, their 
only form of theater entertainment. In this, however, they have 
been doomed to disappointment, for economic and other considera- 
tions have pushed the development of sound pictures to the almost 
total exclusion of the silent variety. 

The fact that the hard-of-hearing belong to a minority group com- 
pared with those with normal hearing should not obscure the impor- 
tance of adding them to the list of theater patrons. By so doing the 
theater will have increased its potential patronage by approximately 
10 per cent. In addition to the possible financial gain created by 
drawing its patronage from a more populous community the theater 
secures general goodwill in its performance of a humanitarian 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Electrical Research Products, Inc., New York, N. Y. 



F. H. GRAHAM [j. s. M. P. E. 


Trustees of the Coolidge Fund for the Deaf estimated the number 
of hard- of -hearing persons in the United States to be 10,000,000. l 
Other estimates as high as 15,000,000 have been made. Obviously, 
these people do not all have the same degree of deafness. The hearing 
of any ear for a particular sound is commonly expressed in terms of the 
intensity level of the sound just audible to that ear compared with 
the threshold intensity required for a normal ear. If we represent 
these threshold intensities by / and 7 6 , respectively, the hearing loss, or 
gain, of the ear under test is given in sensation units (SU)* by 10 log 




10 20 30 40 50 60 70 80 90 100 110 120 130 


FIG. 1. 

Estimated hearing ability of representative group of people 
relative to an average normal. 

There has been recorded by various investigators a certain amount 
of quantitative data showing the results of hearing measurements on 
a number of persons. In making measurements of threshold inten- 
sity on a group of persons having normal hearing, H. Fletcher and 
R. L. Wegel 2 found it to vary over a range of about 30 SU. Twenty- 
two per cent of the supposedly normal group tested were, on later 

* The decibel is the logarithmic unit commonly used to express the ratio of 
two amounts of power. When it is used in describing the magnitude of sounds 
heard by the ear this unit is generally termed sensation unit, and it represents 
approximately the smallest change in the power level of a sound which the ear 
can detect. 


otological examination, found to class as subnormal. 3 Tests on 
school children 4 ' 6 ' 6 have fixed the proportion having subnormal hear- 
ing at from 4 to 8 per cent, with some estimates exceeding these 
figures. C. C. Bunch, 7 on testing groups arranged according to age, 
found that acuity of hearing decreased with age. The 1920 U. S. 
Census classes only 0.04 per cent as deaf mutes. 

Using the statistical data contained in the references cited, we have 
constructed the chart in Fig. 1 showing the probable distribution of 
the hearing ability at a pitch of 1024 cycles per second of the people 
of the United States. The total population is divided into groups 
expressed as a percentage of the total, the hearing loss of each group 
differing in steps of five sensation units from the average normal. 
Since the form of this chart will depend upon the pitch at which the 
hearing is measured, 1024 cycles per second was chosen as being 
fairly representative of the speech frequency range. 

Admitting the obvious approximation of this chart, it will serve 
in the absence of more accurate data to show us the nature of the 
problems involved in supplying sound satisfactory to everyone. For- 
tunately the majority, comprising about 85 per cent of the population, 
fall in the normal-hearing range. In ordinary life surrounded by 
every-day noises a hearing loss of 30 SU or more handicaps us in con- 
versation and in receiving programs at a conversational level. In 
quiet places a smaller, and in noisy locations a larger, amount of 
hearing loss can be tolerated. This can be explained by the fact that 
the effect of noise upon a normal ear is very similar to the 
effect of partial deafness, and by the natural tendency in the presence 
of noise to raise the level of the voice or to step up the volume of re- 
produced programs in order to over-ride the noise level so that a 
normal ear can hear. On the chart possibly 5 per cent of the popula- 
tion fall in the doubtful class where good reception under average 
conditions is problematical. The remaining 10 per cent are classed 
definitely as hard of hearing. This group cannot with any degree 
of satisfaction hear programs designed for normal-hearing audiences. 
Referring to the chart, at least 98 per cent of the population can be 
expected to have 50 per cent or more of their hearing or a hearing-loss 
of no more than 65 SU. 


Fig. 2, a chart published by H. Fletcher 8 shows the relation be- 
tween articulation and volume of received speech. The volume is 



[J. S. M. P. E. 

given in terms of initial speech intensity defined as that received by 
a normal ear with the speaker talking directly into the ear. The 
articulation is the percentage of sounds received correctly. Seventy 
per cent articulation is considered as a fair minimum value which will 
provide good intelligibility. Twenty-five per cent is sufficient to al- 
low us to carry on a conversation. 

The normal ear can accommodate itself over a wide range of volume, 
as can be seen by referring to the curve in Fig. 2 designated as 100 
per cent hearing. To illustrate the limitations imposed by deafness, 
let us take, for example, an ear having a 65 SU hearing-loss at a pitch 
of 1024 cycles per second. The articulation vs. volume relationship 


O eo 






FIG. 2. Volume vs. articulation of undistorted speech for various 
degrees of hearing. 

for this ear, which is given by the curve designated 50 per cent hearing, 
shows that initial speech intensity is required to allow a maximum 
possible articulation of 70 per cent. To obtain this amount requires 
high-quality transmission without distortion. Very little can be 
gained by increasing the volume much above this point due to its 
producing painful sensations in the ear. A transmission system which 
distorts the speech received by the ear having 50 per cent hearing 
will lower the maximum possible articulation below 70 per cent and 
make good reception impossible. From this we can see why the hard- 
of-hearing are critical as to the volume and quality of the sounds 
supplied them. 

March, 1931] 




To meet the requirements of the hard-of-hearing, a system designed 
to aid them in receiving theater programs should transmit with a 
minimum amount of distortion a volume of sound somewhat greater 
than initial speech intensity. For Western Electric high-efficiency 
type head receivers an energy level of one-hundredth of a watt in 
each receiver is ample to furnish all possible needs. Sufficient range 
of volume control must be provided to allow a selection of the proper 
volume to suit each hard-of-hearing patron. In addition, the ap- 
paratus should be comfortable to use. It should allow maximum 
freedom of movement to the user and to his neighbors as well. Tak- 
ing into account the sensibilities of the hard-of-hearing it should be 
unobtrusive in appearance. 



|. 2 



J o 

00* WATT! 



1 [-.*- T 













1 ' 1 








J L ^ OT11I Ho 







1 <v-1 TO SOUND 


FIG. 3. Circuit for deaf-set attachment system. Capacity, 30 seats. 

The theater management obviously cannot tolerate any detractions 
from the normal performance, such as clicks or loss of volume in the 
sound system. In particular, sounds escaping from the receivers are 
objectionable to normal-hearing patrons, due to the phase difference 
existing between these sounds and those received from the screen 


In Fig. 3 is shown the schematic circuit of a deaf -set attachment for 
Western Electric Sound Systems. The attachment consists of a 



[J. S. M. P. E. 

FIG. 4. Showing individual equipment for hard-of-hearing in operation. 


network which diverts a small amount of power from the sound-sys- 
tem amplifier, an amplifier which raises this power to a level high 
enough to supply the number of receivers required, a seat- jack unit 
containing two jacks for every two seats to be equipped, and a tele- 
phone set for each hard-of -hearing patron. The telephone set con- 
sists of a receiver, a small volume control inserted in the receiver cord 
and a plug to connect the telephone set to the seat- jack. 

The energy levels shown in Fig. 3 are those for a system capable 
of supplying from one to thirty seats. Other amplifiers having 
higher output capacities are available where more than thirty seats 
are to be equipped. The head-set system operates as a unit with the 
sound system and does not require the attention of the sound system 

Fig. 4 shows the individual equipment for the hard-of-hearing in 
operation. The seat-jack unit is mounted on the front seat standard 
just under the arm of the seat. The volume control is contained in 
a small cylindrical case, which for convenience and ready access is 
held in the hand. The receiver is held to the ear by a headband which 
permits the user freedom of movement. The headband obligates 
the observer to keep the receiver on his ear while it is in use, thus 
minimizing the sound escaping into the air. 

We have shown the attachment linked with the regular sound pic- 
ture system. When public address facilities for stage reenforcement 
are available, the hard-of-hearing can hear the stage presentations as 
well as the sound pictures. For amplifying stage programs where a 
sound system is not installed, an acoustic pick-up equivalent to that 
of the public-address system must be used. 

A word of caution should be inserted in dealing with the problem of 
the hard-of-hearing in theaters. For reasons pointed out, those who 
have only a small percentage of hearing remaining cannot be guaran- 
teed to be made to hear, irrespective of the type of hearing-aid in- 
stalled. In fact, little good would result in encouraging them to try 
since their reactions must be unfavorable and will probably tend to 
discourage others from making use of the system. Similarly, the 
use of a system which alters the character of the sound by reason of 
poor transmission characteristics or by superimposed noises, or of a 
system which does not contain essential fundamentals of design, 
will increase the number of people who cannot use it satisfactorily. 
By such methods the movement to bring the hard-of-hearing into 
the theaters will be retarded. 

348 F. H. GRAHAM 


1 "Coolidge Fund for the Deaf," N. Y. Times (April 14, 1929). 

8 FLETCHER, H., AND WEGEL, R. L. : "The Frequency Sensitivity of Normal 
Ears," Proc. of the National Academy of Sciences (January, 1922). 

FOWLER, E. P., AND WEGEL, R. L.: "Audiometric Methods and Their 
Applications," Annals of the Amer. Rhin., Larg., and Ot. Soc. t June, 1923. 

4 FOWLER, E. P., AND FLETCHER, H.: "Three Million Deafened School Chil- 
dren," //. of the Am. Med. Assoc. (Dec. 4, 1926). 

6 FOWLER, E. P., AND FLETCHER, H.: "Deafened School Children, Detection 
and Treatment," Jl. of the Am. Med. Assoc. (Oct. 20, 1928). 

6 FLETCHER, H. : "The Progress of Hearing-Tests in the Public Schools of the 
United States," Trans. Am. Child Health Assoc. (Sept. 30, October 5, 1929). 

7 BUNCH, C. C.: "Age Variations in Auditory Acuity," Archives of Otolaryn- 
gology (June, 1929). 

8 FLETCHER, H. : "The Use of the Audiometer in Prescribing Aids to Hearing," 
Trans, of the College of Physicians of Philadelphia (1923). 



Summary. In connection with the installation, operation, and repair of am- 
plifier equipment as used in the motion picture industry, various electrical measure- 
ments are necessary. In order to carry out these measurements, a portable test set 
was designed. This test set was arranged to measure the various voltages and currents 
encountered in amplifying equipment and in addition, means were provided for testing 
circuits, amplifier and rectifier tubes, and for measuring resistance and capacitance. 

Since the motion picture theater is the main outlet for the products 
of the motion picture industries, it seems that anything reasonable 
which will keep the show running, and, which is quite as important, 
keep it producing satisfactory results, is worth considering. Equip- 
ment of all kinds requires periodic attention, adjustments, and 
occasional replacement of parts. 

In order to facilitate this work, a portable test set for assisting in 
the servicing of sound-picture equipment is hereby suggested. As 
with practically all kinds of apparatus a compromise must be made 
between the desired and the attainable. So, with this test set, if we 
were to design it for all the tests possible, portability would be sacri- 
ficed and it would become useless for field work. It has been de- 
signed, therefore, to perform only the essential and necessary tests. 

Since the heart of the reproducing system is the amplifier tube, 
suitable testing facilities are provided so that in the event of trouble 
these tubes may be tested both in conjunction with the amplifier 
equipment and independently of it. The use of apparatus for measur- 
ing the characteristics of amplifier tubes, because of its bulk and 
weight, is restricted to laboratories and service stations. However, 
a simple, rapid test is quite essential at the time of installation and at 
regular intervals thereafter, as routine inspection. The amplifier 
tubes most commonly used in amplifier installations are the types 
112-A, 245, 210, 250, 171-A, 227, 226, 845, 239, 205, 211, 280, and 281, 
the last two being rectifier tubes. 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Western Electrical Instrument Corp., Newark, N. J. 


350 A. H. WOLFERZ [J. a M P. E 

The commercial 60 cycle alternating current supplied by the light- 
ing mains is used. The filament or heater of the tube being tested 
is connected to the secondary of a transformer having a variable pri- 
mary, so that its turn-ratio may be altered to compensate for varia- 
tions in the line voltage. An a-c voltmeter is connected across the 
filament or heater so as to indicate when the correct value is obtained. 
The plate circuit voltage is approximately 120 volts and the grid is 
connected to one side of the filament or heater, providing a bias such 
that approximately the rated plate current is obtained. The grid 
potential is made less negative, causing the plate current to increase 
when a good tube is being tested. When the tubes are old or defective 
the change of plate current becomes very small or is not noticed at all. 
When making this test the rated values of plate and grid potentials 
are not applied to the tube. It is, however, a useful test when trouble 
exists which causes the equipment to be incapable of producing proper 
operating voltages. 

When the amplifier equipment is capable of supplying to the tubes 
the normal filament, grid, and plate voltages, the tubes may be tested 
under operating conditions. The tube to be tested is removed from 
the. socket on the amplifier panel and inserted into a socket provided 
on the test set. The test set is provided with a cable terminated by 
a plug which is inserted into the socket on the amplifier panel. When 
this connection is made, the value of the plate current is indicated by 
the plate milliammeter of the test set. On pressing a switch the 
grid is made less negative, causing an increase of plate current. 

After testing a number of good tubes under these conditions, an 
average value of increase can be determined. As with the previous 
test, a slight increase or no increase of plate current indicates that 
the tube is below normal or is unfit for further use. 

A third method of testing tubes may be provided which also em- 
ploys the filament, grid, and plate potentials as they exist at the ampli- 
fier panel, but, instead of obtaining two values of plate current for 
a change of grid potential, the circuit is so arranged that the plate 
current remains constant. 

The tube is inserted into the socket provided on the test set, the 
latter being connected by cable and plug to the socket on the amplifier 
panel. The plate current corresponding to normal plate, grid, and 
filament voltages is noted. A switch is pressed which introduces 
a resistor into the plate circuit and then reduces the grid potential 
to zero. This resistance, connected into the plate circuit, is so pro- 


portioned that when a normal tube is tested no change of plate cur- 
rent is observed. The magnitude of the change is a measure of the 
inferiority of the tube. 

The values of filament or heater voltage, grid voltage, plate voltage, 
plate current, and cathode voltage, measured at the sockets of the 
tubes on the amplifier panel all serve to check the remainder of the 
equipment. For example, should the heater voltage be too high or 
too low this could be caused by improper adjustment for line voltage. 
A lack of heater voltage may indicate an open transformer or lead 
wire. Improper plate voltage may be caused by a defective rectifier 
tube, a defective high potential transformer, faulty condensers, etc. 
Improper plate current may indicate an improper grid potential. 
Improper grid voltage may be caused by a defect in the resistance 
used to obtain this potential or by a defective grid battery. When 
making these tests it is only necessary to remove each amplifier or 
rectifier tube in turn and place it into the socket provided on the test 
set; the test set is then connected by means of the cord and plug, to 
the socket on the amplifier panel. The instruments on the test set 
have suitable ranges for properly measuring the various currents and 
voltages, and suitable switches for connecting these instruments, with 
their respective ranges, into circuit. All instruments used on the 
test set have bakelite cases or are otherwise insulated to protect the 
operators. The voltmeter used to measure the filament, grid, plate, 
and cathode voltages is of the permanent-magnet, movable-coil type, 
and requires less than one milliampere for full-scale deflection. Its 
readings may be relied upon to within one per cent of the full-scale 
value, and will indicate voltages from about 1 to 1500 volts. 

The milliammeter of the test set used for measuring plate current 
is also of the permanent-magnet, movable-coil type, and has the same 
scale-length and accuracy as the voltmeter, with ranges suitable for 
carrying out the tests. Ranges up to 300 ma. should prove satisfac- 
tory. A desirable feature is the range-changing switch, having a 
spring control which leaves the milliammeter always set for its highest 
range, preventing possible damage when defective tubes or circuits 
are encountered. 

The voltmeter provided to measure the heater voltage of a-c tubes, 
a-c line voltage, or transformer secondary voltage, is of the movable- 
iron type, with a scale-length and accuracy such that readings are 
correct to within two per cent of the full-scale value. Errors due 
to temperature changes, etc., are within this value and provision is 

352 A. H. WOLFERZ [J. S. M. P. E. 

made for preventing the series resistors from overheating and altering 
the voltages which it is desired to measure. That such qualifications 
are quite important may be realized when it is considered that volt- 
ages from approximately 1 volt to 3000 volts are encountered and 
suitable ranges and switches are necessary in order to carry out these 

The d-c voltmeter is also designed so that it may be used to measure 
resistances of circuits or parts of the apparatus, or to test for conti- 
nuity of the wiring of circuits. The type of resistances encountered re- 
quire that it be capable of giving an accuracy of about two per cent 
for resistances from about 10 to 100,000 ohms. A small battery is 
self-contained in the case, connected so that its voltage changes may 
be compensated for. It is easily removable for replacement and is of 
a standard size readily purchased. 

It is very desirable to have a means for measuring the a-c output 
voltage at various places in the amplifier system or across the voice- 
coil of the speakers. This requires an a-c voltmeter with a number 
of ranges, consuming a small amount of power and having a fixed 
value of impedance; a value of 4000 ohms is generally used. A very 
convenient method is to use a permanent-magnet, movable-coil 
instrument in conjunction with a rectifier. Copper-oxide rectifiers 
are used, giving very satisfactory results for this type of test work. 
If this meter is used in conjunction with a test record or film having 
an assortment of frequencies, a very convenient and useful test 
may be made of the complete installation, which should also prove 
of value in determining the relation of modulation to ground noise. 
The scale may be calibrated in terms of effective values or a curve 
can be employed to allow the use of the d-c scale already on the meter. 

Numerous condensers are employed in the amplifier circuits, and 
the test set is also designed to measure capacitance to a fair degree 
of accuracy. This is accomplished by using a low-voltage range 
of the a-c voltmeter, in series with a suitable resistance and the 
condenser to be measured, connected to a source of alternating current 
of known frequency and voltage. The voltmeter then simply acts as 
a milliammeter and indicates the current flowing in the circuit. 
Marks are provided on the scale of the instrument by previous calibra- 
tion with reference to known condensers connected in series with a 
60 cycle, 115 volt supply. Marks corresponding to 1, 2, 4, and 8 
microfarads are provided on the scale, and a curve plotted from 
these can be used where more accurate readings are desired. The 

March, 1931] 



adjustable series resistance affords a means of compensating for line 
voltages higher or lower than 115 volts. The adjustment is made by 
first closing the circuit where the condenser is to be inserted, and then 
adjusting the resistor until full-scale deflection of the instrument is 

Fig. 1 shows the arrangement of a set provided with means for 
making the tests and measurements outlined above. 

Beginning at the upper-left of the panel, there will be found a fuse 
connected in" the filament circuit; along the upper part of the panel 

FIG. 1. Top view of test set for servicing motion picture equipment. 

will be found sockets for the various tubes mentioned. There are 
shown, from left to right, a socket for 211, 845 or similar tubes, a UY 
socket for all 5-prong heater tubes similar to the 227, a socket for 
W.E. 205 tubes, and last the UX socket for all standard 4-prong 
tubes as the 112, 171-A, 245, 210, 250, 226, 239, 280, and 281. 

The instrument on the left is the milliammeter for plate-current 
measurements; its ranges are selected by the switch directly below 
the right-hand instrument, providing for ranges of 3, 75, 150, 300 
ma. Regardless of the setting of any switch, this milliammeter 

354 A. H. WOLFERZ [j. S. M. P. E. 

with its shunts is always connected in the plate circuit. Its ranges 
are also available for other measurements by using the binding 
posts marked "Milliamperes D.C.", at the lower right-hand corner. 

The instrument in the center is the combination a-c voltmeter, 
milliammeter, and ammeter. It is a movable iron type of instrument 
and will also indicate when direct current is used. However, more 
current is required to operate it than is required for the d-c voltmeter, 
so that it could not, therefore, be used as a substitute for the latter. 
A two-winding, two-circuit field coil is used, allowing for ranges of 
4, 8, and 16 volts requiring a current of exactly 100 ma. for full-scale 
deflection, and all errors are kept small enough to provide an accuracy 
of two per cent of the full-scale value. Ranges of 150, 300, 750, 
1500, and 3000 volts, requiring exactly 20 ma. for full-scale deflection, 
are provided. The low ranges are for use in measuring filament or 
heater voltage, and are available for use with the plug and cable or at 
the binding posts. The higher ranges are for line voltage and trans- 
former secondary voltage. These measurements can be made only at 
the binding posts at the left-hand edge of the test set. An additional 
winding is provided for ranges of 4 and 8 amperes, which may be used 
for measuring line currents. Marks are drawn on the scale corre- 
sponding to 1, 2, 4, and 8 microfarads, using 115 volts, 60 cycles; 
the rheostat at the lower left provides the compensation for line volt- 

The instrument at the right is the volt-milliammeter. This is also 
a permanent-magnet, movable-coil instrument, and is principally 
used to measure filament, grid, cathode and plate voltages when the 
test set is connected to the amplifier panel by the cord and plug. Its 
ranges of 3, 7.5, 15, 30, 75, 150, 300, 750, and 1500 volts and the con- 
nections for making these measurements are brought into circuit by 
the double-pole multiple switch shown directly beneath the a-c 
voltmeter. A shunt is provided in the grid circuit so that this meter 
may be used to measure one of the plate currents when full wave 
rectifier tubes are tested. All the ranges are available at the binding 
posts shown at the right edge of the test set. A circuit is also provided 
for measuring resistance, including a self-contained 3-cell battery, 
a variable resistance shown below and to the right, and the binding 
posts marked "Resistance Test." It is first necessary to short cir- 
cuit the binding posts marked "Resistance Test" in order to first 
adjust the variable resistance for full-scale deflection of the meter. 

The short circuit is then replaced by the unknown resistance to 


be measured. A scale is provided having ranges of to 10,000 and 
to 100,000 ohms, permitting values of resistance to be read directly. 

The two-pole, multiple switch is provided with a position to allow 
this instrument to be used with a copper-oxide rectifier for measure- 
ments of output voltage. Suggested ranges would be 3, 30, and 150 
volts, each with an impedance of 4000 ohms. The other switches on 
the panel are to bring about the tests and measurements previously 
referred to, such as changing the grid potential, measuring transformer 
secondary voltage, and reversal of the d-c voltmeter. 

The test set may be used for other tests about the theater such as 
line voltage measurements, measuring resistance of circuits, tracing 
for open or short circuits, loud speaker voltage or currents, fuse test- 
ing, battery voltage tests, and many other tests which will present 
themselves with experience. 



Summary. An instrument for obtaining full-screen motion pictures of the vocal 
cords at the rate of 16 frames per second is described. A laryngoscope, illuminating 
system and viewing finder , are combined into a self-contained diagnostic unit. The 
problem of lighting is solved by using a quartz rod which directs the light from a small 
incandescent lamp to the larynx. 

Many early attempts to photograph the larynx were made, but 
it was not until 1884 that T. R. French 1 succeeded in obtaining con- 
sistently good results, using the sun as an illuminant. In 1897 2 he 
had successfully applied the arc lamp to the problem. Although 
the motion picture reached a practical state shortly after this no 
results of its application to laryngeal photography were reported 
until those of Panconceilli-Calzia 3 in 1920. The need of relatively 
long exposures under the poor lighting conditions constantly de- 
feated the attainment of satisfactory photography at normal speeds. 

Some problems connected with the early development of medical 
films made necessary the investigation of the possibilities of obtain- 
ing motion pictures of the vocal cords. For this purpose it is highly 
desirable to obtain full-screen pictures. In these experiments, 
encouraged by Dr. Richard S. Lyman, Dr. Clyde A, Heatly assisted 
in preparing patients and in passing the instrument. This asso- 
ciation led to Dr. Heatly's suggestion that the apparatus be de- 
veloped for clinical use as an aid in the study of the pathology of 
the larynx. The apparatus described in this paper is a solution of 
the problem. 

An instrument of this type must necessarily be as simple to use 
and handle as a camera, in order that the physician may not be much 
more encumbered than if he were using an ordinary form of the 
laryngoscope. The crux of the problem of obtaining full-frame 
motion pictures at the rate of sixteen frames per second lies in 
sufficiently illuminating the larynx without interfering with the 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Eastman Teaching Films, Inc., Rochester, N. Y. 



limited channel by which light reaches the camera lens. This 
difficulty was overcome by using a quartz rod by means of which a 
large quantity of light is carried through the tube of the laryngoscope 
without encroaching seriously upon the field. 

Fig 1 is a side view of the instrument. Fig. 2 is a bottom view, 
showing the plan of the optical system as is diagrammatically illus- 
trated in Fig. 3. The unit consists of a model B Cine- Kodak at- 
tached to a metal plate, which also serves to hold the laryngoscope 
and illuminating system. A viewing system is fastened to the side 
of the camera. 

FIG. 1. Side view of camera and attached laryngoscope. 


An //3.5, 50 mm. objective lens replaces the standard one of 25 
equivalent focal length. This is so placed that the object 
plane lies 19 mm. in front of the lip of the tube on the laryngoscope. 
A lens of larger relative aperture would reduce seriously the depth 
of focus. Illumination is provided by a 21 cp., 6 volt automobile 
headlight bulb, using a voltage 50 per cent greater than the rated 
value. Both filaments are used simultaneously. A condenser of 
high relative aperture consisting of three spectacle lenses, having a 



[j. S. M. P. E, 

FIG. 2. Under view of laryngoscope and camera. 

March, 1931] 



power of twenty-two diopters and so chosen to give the least 
spherical aberration, has a free aperture of 41 mm. and an equivalent 
focal length of 45 mm. This condenser images the filaments of the 
bulb at the end of the quartz rod, the end of which is ground to 
form a 45-degree prism. The prism, silvered on the hypotenuse, 
reflects the light along the 4 mm. quartz rod from the end of which 
the light is virtually sprayed over the photographic field. The 
center of interest lies somewhat off the axis away from the lip 
of the laryngoscope; therefore, the end surface of the rod is ground 
to form a 15- degree prism in order to center the light on the field. 

u ^~ 

A rr\rf\ 

nijorf? rfln 

jz mm. 
Mirror Micro Objective 

5x Micro Eyepiece 

. A 



/ j 

&^%5j Micro Objective 


EV -44 1 



irf; vx | 
A\ Camera 
v \ Objective 

sVKJ Lenses 


_ \ \NO.IIIO 
" } /Headlight bulb 

100 mm. 

FIG. 3. 

Schematic diagram of the optical system of camera, lighting 
system, and finder, attached to laryngoscope. 

This method of illumination provides a cool light with an intensity 
of 400 to 600 foot-candles on the larynx. 

A par-focal viewing system is attached to the side of the camera 
and enables the operator to focus the instrument on the vocal cords 
and to observe the field while the camera is running. The entire 
system is conveniently formed by a combination of microscope 
optics or their equivalent. A 48 mm. objective is used, stopped 
down by a 3 mm. diaphragm. The erecting system is a 32 mm. 
objective and the eyepiece is a 5x ocular. The field is seen by the 
eye in the same position as it will appear on the screen. The mirror 
attached back of the objective lens of the finder and the 2 mm. 
prism mounted just ahead of it serve to alter the direction of the 



[J. S. M. P. E. 

optical axis for convenient placing of the eyepiece. The small tube 
originally built into the laryngoscope to hold the pea-lamp, which 
served as an illuminant for visual use, is extended to the lip of the 

instrument to serve as an aspirator 
for the removal of excess mucous 
which may collect in the field. 

In using the instrument at room 
temperature there is a possibility 
of moisture condensing on the 
camera objective. To prevent 
this the entire apparatus is warmed 
to about 37C. just before passing 
it into the oral cavity. The heat 
from the lamp housing and con- 
tact with the throat structure will 
hold the temperature at the proper 
level to prevent condensation 
during the taking of the pictures. 
One winding of the camera motor 
usually suffices for the record of 
a patient. 

Fig. 4 is a group of three single- 
frame enlargements from a se- 
quence showing the closing of the 
vocal cords of a normal larynx 
incident to the production of a 
sound. The anterior portion of 
the larynx is in the upper part of 
the field. Although this instru- 
ment is not satisfactory for the 
study of the function of the larynx, 
owing to the presence of the tube 
in the oral cavity and the pharynx, 
it presents a ready means of mak- 
ing case records in which the 
larynx is shown in various phases 
of its movements. 

FIG. 4. Full-frame enlargements 
from a sequence showing closing of 
vocal cords. 


1 FRENCH, T. R.: "On a Perfected Method of Photographing the Larynx," 
New York Medical Journal (Dec., 1884). 

March, 1931] THE LARYNGOSCOPE 361 

2 FRENCH, T. R.: "Laryngeal and Postnasal Photography with the Aid of 
the Arc Light," Ibid. (Jan., 1897). 

3 PANCONCEILLI-CALZIA, G.: "Die Kinematographie und Photographic der 
Bewegungen im Kehlkopf oder im Ansatzrohr auf Grund der Autokatojtrie," 

Vox. BerL, 30 (1920), s. 1. 


. : > 



O. M. GLUNT** 

Summary. Fundamental research and development work carried on with a 
particular objective in one field contributes in many cases to the solution of problems in 
other fields. A typical example is the application of the sound reproducing elements, 
developed for use primarily in sound picture theater reproducing systems, in the 
solution of an intricate problem in telephone system operation. This article outlines 
the communicating problem which was presented and describes the apparatus which 
was developed, employing adaptations of sound picture principles to meet the need. 

It is well known that the fundamental research carried on in the 
telephone field by Bell Telephone Laboratories has served as a basis 
for the development work which it has done in the sound picture field. 
As is to be expected this development work, which produced the sound 
pictures, is also being applied to the solution of problems arising 
within the telephone system. 

One such problem is a result of the present transition from manual 
to dial operation of telephones, in which there are frequently two 
different telephone systems in operation in the areas involved, and it 
is necessary to interconnect these two systems in some manner. 

Suppose, for example, a subscriber connected with a dial operated 
office wished to talk with a subscriber connected to a manually oper- 
ated office. It would be a simple matter to arrange a circuit so that he 
might dial the desired number and thereby select and cause a series of 
pulses to pass over the wire to the manual office. These pulses, how- 
ever, would be unintelligible to the operator. Some means of trans- 
lating these pulses into a signal which she would understand and 
which would give her sufficient information to set up the desired con- 
nection is required. 

This problem first arose a number of years ago, when the installa- 
tion of dial telephones was undertaken on a large scale. It was 
then solved by the use of the "call indicator," in which the pulses 
from the dial telephone caused certain numbers and letters to be dis- 
*Received by the Editor, February 1, 1931. 
**Bell Telephone Laboratories, New York, N.Y. 



played before the operator. This apparatus, however, was limited 
in use to circuits of relatively short length. The terminal equipment 
was expensive and for the smaller suburban offices it could not be 
"proved in." 

These objections were not important as long as the use of the call 
indicator was limited to setting up local calls in city offices. With 
the growth of the dial system, however, dialing was used to set up 
connections over longer and longer distances, and it became evident 

FIG. 1. Call-announcing apparatus with covers removed. At the top 
can be seen the driving motor and the 8 drums, each bearing 8 strips 
of film. Associated with each strip of film is an exciting lamp, optical 
system, and photo-electric cell. 

that the call indicator would have to be replaced or supplemented by 
some other type of apparatus which would be generally applicable to 
the telephone system, of relatively low cost, and which in operation 
could be adapted to existing practices. It was therefore decided to 
determine the possibility of translating the pulses of the dial into 
speech, as such speech could naturally be carried anywhere over the 
telephone system. 

After some preliminary investigations, such as a series of measure- 



[J. S. M. P. E. 

ments on the time duration of spoken digits, work on the first experi- 
mental apparatus began in 1927. There had been public showings of 
sound pictures for almost a year, and the sound picture industry was 
entering upon a period of intensive growth. For this reason there 
was available a rapidly growing wealth of sound reproducing ap- 
paratus together with experience in its operation. This was of great 
value in the development of the "call announcer." 
The first call announcer consisted of a large brass drum with four- 

FIG. 2. Commercial installation of call-announcing apparatus. At the 
left can be seen the frames carrying the telephone repeaters which form 
the last stage of amplification, together with other telephone apparatus. 

teen slots running around it. Over each of these slots was placed a 
sound film one for each of the digits, and one for each of the call 
letters, J, M, R, W. Inside the drum and associated with each of 
these strips of film was a lamp and a lens system which focused the 
light from the lamp on the film. After passing through the film, the 
light was picked up by a photo-electric cell outside the drum. The 


March, 1931] 



electrical output of the cell was then passed through a three-stage 
amplifier associated with it. By means of relays actuated by the 
dialing pulses the proper film reproducing circuits were connected in 
the correct order to inform the operator of the number dialed. 

During the latter part of 1927, the feasibility of the project was 
demonstrated with this first model, and it was determined to proceed 
with the work. The question immediately arose as to the compara- 

FIG. 3. Three typical strips of sound film as used on 
the call-announcer drums slightly enlarged to show the 
characteristics of the sound track of the recorded char- 
acters 1, W, and 9. 

tive length-of-life of film and disk sound records. The importance 
of this in a call-announcing mechanism for the telephone system can 
be readily appreciated from the fact that it must be possible to play 
the record continuously many thousand times a day over a long period 
of time with a minimum amount of replacement. 

Under the conditions met in sound picture projection, neither film 
nor disk records entirely satisfy this requirement. Disk records 
would need replacement much more frequently, as would the pick-up 

366 O. M. GLUNT [j. s. M. p. E. 

needle. From the standpoints of cost for records and of attention in 
operation the film record was selected in preference to the disk. 

The question of replacements also arose in connection with the 
lamp and photo-electric cell which, as used in a sound picture pro- 
jector, have an average useful life of 150 and 1500 hours, respectively. 
Due to the intermittent use of sound picture projector equipment, 
short-lived consumable items such as lamps are not a serious opera- 
tive matter as long as they involve only a small cost. In the call 
announcer, due to their continuous use, the frequent replacement of 
these elements would present a serious operating obstacle quite apart 
from the cost of replacement. Fortunately, the needed signal level 
conditions of the call announcer made it possible to depart from the 
sound picture operating practice. This departure consists in operating 
the lamp at a much lower illumination level, obtaining a longer operat- 
ing life for lamp and cell. As a result, the average life of these ele- 
ments in a call announcer under normal conditions is about 200 days. 

While the final form of the call announcer is much the same as in 
the first experimental model, a number of changes have been made. 
The photo-electric cell is now inside and the lamp and lens system are 
outside the drum, making it easier for the heat generated by the lamp 
to be carried away, thereby prolonging the life of the film. Other 
advantages of this arrangement are the greater accessibility of the 
various parts and the ability to use a greater amount of standard 
sound picture apparatus. 

In its present form the apparatus includes a group of eight drums. 
These drums are arranged to carry four strips of sound film on each 
outer edge. One of these drums is a spare and each of the other seven 
carry two groups (4 strips each) of sound film ; a total of 14 groups. 
On each of the four strips of the 14 groups is recorded one of the ten 
digits or one of the four call letters J, M, R, and W. These drums are 
mounted on a common shaft and are driven by a small motor through 
a suitable reduction gear to give a constant peripheral drum speed 
of 90 feet per minute. In front of each film is a small lamp which 
is focused on the film by means of an optical system and behind each 
film and within the drum is a photo-electric cell. 

The drum on which the film is mounted must be large enough to 
permit a photo-electric cell to be mounted within the shell. This re- 
quires a circumference much greater than that required for a single 
repetition of a number or letter; four announcements of the number 
or letter are therefore recorded, one on each piece of film, and these 

March, 1931] THE CALL ANNOUNCER 367 

four strips are mounted symmetrically around the circumference of the 
drum. The actual speaking time required for a single digit is about 
0.27 second, and the silent interval allowed is 0.08 second. These 
values are for a film running at the standard speed of 90 feet a minute. 

The three-stage amplifier associated with each of the sixteen (in- 
cluding two spares) sound reproducing systems is located just beneath 
and in front of the rotating drums. By means of these amplifiers 
the current from the photo-electric cell is brought up from an acoustic 
level of about 70 or 75 db. to a level of about 25 db. From 
these amplifiers, the current is fed into telephone repeaters mounted 
on an associated relay rack, which act as final power amplifiers and 
bring the acoustic level up to approximately the zero reference point, 
6 milliwatts. When a number is dialed, it is recorded on relays in the 
sending mechanism, where it remains stored until the operator who is 
to complete the call is free to do so. She then pushes a button and 
the relays, in which the number is stored, actuate other relays to cut 
in the proper films in the correct sequence in order to announce to the 
operator at the manual board the number which has been dialed. 

These call announcers, at least for the present, will not be placed 
in dial exchange offices, but only in dial tandem offices, which are 
used to connect widely separated telephones. Three call announcers 
will be placed in each of these offices, one of which is held in reserve, 
the load being automatically distributed between the two in service. 
The call announcers in service are monitored automatically by relays 
in each reproducing circuit. These relays are held operated as long 
as the reproduced speech in each circuit is maintained at a predeter- 
mined level. If, through failure of the photo-electric cell, the lamp, 
or from any cause, the volume falls appreciably in any reproducing 
circuit, the particular call announcer is switched out of service and 
the spare one connected in its place and a signal is given to the main- 
tenance force. 

Development work on the call announcer was completed and a 
public demonstration was made in 1929. It was demonstrated to 
members of the Society on the occasion of their visit to Bell Telephone 
Laboratories during the Fall Meeting, October 20-23, 1930. This 
apparatus has given entire satisfaction in the numerous tests made 
with it and the first commercial installation was put into service 
January 3, 1931. 

*Due to the lower illumination level of the lamp, this current is much less than 
in sound picture practice. 


New Committees. The following new committees have been 
appointed : 

Practical Projection 

H. RUBIN, Chairman J. HOPKINS 

T. BARROWS R. H. McCuixouGH 





Projection Theory 

W. B. RAYTON, Chairman 

Two additional committees are in process of formation which will 
deal with projection screens and fire protection. The Color Com- 
mittee is arranging for an exhibition of representative films prepared 
by the various commercial color processes at the Spring Convention. 
The Historical Committee is likewise arranging for an exhibit of 
apparatus and films of historical interest. 

Meeting of the Practical Projection Committee. The first meeting 
of this new committee was held at the Paramount Building, . New 
York, on Wednesday evening, January 21, 1931. Chairman H. 
Rubin, in his introductory remarks, stated that the meeting was 
called for the purpose of gathering technical information relating to 
the practice of projection, and to make a report to the Society at the 
Spring Meeting. In discussing the ideal lay-out of the projection 
room, the chairman remarked that it would be necessary to deal 
with its location, size, equipment, safeguards, ventilation, painting, 
lighting, wiring, etc., and lay-outs suitable for vaudeville theaters, 
regular theaters, and de luxe houses should be prepared. Recom- 
mendations should also be secured from acoustical experts relating 
to the best treatment for lessening noise in the projection room. 
The distance between projector centers as related to the projection 


distance and the matter of auxiliary automatic ventilation as an 
emergency safety measure should be considered. 

Mr. J. H. Goldberg presented to the chairman three sets of pre- 
liminary lay-outs for projection rooms for class A, B, and C theaters 
and these blue-prints and plans were discussed. A subcommittee 
was then appointed to prepare an ideal projection room lay-out for 
large, medium, and small theaters. The committee is composed of 
the following members : 

J . H. GOLDBERG, Chairman 

Mr. F. H. Richardson then moved that the Practical Projection 
Committee should consider holding a meeting with theater archi- 
tects or representatives of their association for discussing the ideal 
projection room lay-out and its location with respect to each type 
of theater mentioned above. This motion was carried and Chair- 
man Rubin promised to make the necessary arrangements. 

The problem of the relation between screen brightness and the 
illumination level in the auditorium, in so far as it affects the eye- 
sight of the observer, was referred to the Projection Theory Com- 

The following subcommittees were also appointed: 

Screen Illumination 

( To investigate and prepare standards for proper screen illumination as contrasted 
with the illumination level in theater auditoriums.} 

H. GRIFFIN, Chairman 

Projection Room Routine and Maintenance 

(Embodying daily inspection of equipment and preparatory work to insure perfect 


J. J. HOPKINS, Chairman 




Monitoring and Control of Sound in Theaters 

H. B. SANTEE, Chairman 






Progress and Improvements in Projector Design and Accessories 

H. GRIFFIN, Chairman 

The problem of film buckle was referred to President Crabtree 
for consideration by some other committee. The subcommittee on 
"Progress and Improvements in Projector Design and Accessories" 
will also consider this question. 

The chairman briefly described a new curved film track which 
was designed to aid in the projection of buckled film and announced 
that a technical paper on this device, written by its inventor, will be 
submitted to the committee at the next meeting. 

The new standard release print was discussed and Mr. Richard- 
son voiced an objection to the black circle motor and change-over 
cues which are now a part of the standard change-over practice. 
The chairman ruled that the standard should be given a further 
chance to function before any changes are advocated. 


A Meaningless Jubilee. G. SEEBER AND K. WOLTER. Filmtechnik, 6, 
November 15, 1930, pp. 1-4. The suggestion of a celebration for the Sklada- 
nowsky brothers prompts an editorial chronological review of the beginnings 
of motion pictures in the various countries. The article points out the fallacy 
of any claims that the Skladanowsky brothers gave the first public showing of 
motion pictures. The date of their showing in Berlin was November 1, 1895, 
long after the public exhibitions of Edison, Jenkins, Paul, the Lumiere brothers, 
and Acres. L. E. M. 

Damage to Sound Films in Projection. A. SZEKELY. Filmtechnik, 6, De- 
cember 13, 1930, pp. 9-10. The suggestion is made that the projection life of 
sound films is low because of drying out during the time that the films are threaded 
in the projectors and exposed to temperatures of 35 C. to 40 C. Such troubles 
may be minimized by using larger sprockets and better idler devices for keeping 
the film on the sprockets. L. E. M. 

Sound Film's Production Cost Near Ten Times That of Silent. Ex. Herald- 
World, 101, December 27, 1930, p. 7. According to a preliminary report of the 
U. S. Census Bureau, more than 1000 sound films were produced in 1929 at a total 
production cost of $100,000,000, while 1500 silent pictures were turned out 
costing less than $17,000,000. There were 143 establishments included in the 
census and their total expenditure was over $180,000,000, compared with $134,- 
000,000 for 142 concerns reported in 1927. Negative films used in 1929 cost 
$125,000,000 and positive films over $10,000,000. G. E. M. 

Comparative Investigation of Electric Pick-Ups. P. HATSCHEK. Filmtechnik, 
6, December 13, 1930, pp. 12-14. Pick-ups of German manufacture were tested 
for response characteristics. Curves are given which show their behavior over 
a frequency range of 60 to 5000 cycles per second. L. E. M. 

Metal Film for Motion Pictures. Film Daily, 55, January 14, 1931, p. 8. 
Metal film, claimed to be more durable and resistant than the present celluloid 
preparations, is reported to have been invented by L. Lumiere. C. H. S. 

Distortion of a Variable Density Modulation in Printing the Positive. LEEN- 
HARDT. Tech. Cinemat., 1, November-December, 1930, p 11. The negative 
sound record produced in the variable density method of sound recording has a 
logarithmic distortion, on account of which no accurate appraisal of recorded 
sound quality is possible by direct reproduction of the negative. A corresponding 
distortion in the process of printing the positive compensates for it. Mathe- 
matical and graphical demonstration is given for an originally pure sinusoidal 
sound wave. C. E. I. 

Yield of the Fixing Bath in a Machine. R. LANDAU. Tech. Cinemat., 1, 
November-December, 1930, p. 8. In a tube type of developing machine the 
utmost yield of useful work is obtained from the fixing bath by a system of 


372 ABSTRACTS [j. s. M. P. E. 

countercurrent flow. A convenient method of controlling the flow is one which 
takes advantage of the difference in density of the liquid at the last (film) stage 
and at the first where the bath is being diluted by developer carried on the film. 
If all the tubes are connected by small pipes at the bottom, the step-by-step 
change in gravity from one end of the machine to the other will cause a difference 
in liquid level from the first to the last tube. Although each tube is equipped 
with an overflow hole near the top, liquid will overflow only from the one or two 
tubes (of ten) nearest the developer because of the greater dilution with the 
consequent high liquid level. Thus the liquid is always discharged at the di- 
luted (and exhausted) end. (In American practice where the water enters the 
fixing bath from a water rinse, this effect is also present. Abstractor's Note.) 

C. E. I. 

Orthochrome Screen Eases Eye Fatigue. Mot. Pict. Daily, 29, January 20, 
1931, p. 6. A description of a motion picture screen which regulates the spectral 
character and brilliance of the reflected light and thus is claimed to minimize 
eye fatigue. The surface of the screen is divided into a multiplicity of uniformly 
distributed areas, part of which are covered with a light filter, absorbing all or 
part of any predominant wave-length. A surface of uniformly distributed units 
results, each pair of which is claimed to reflect a composite of the wave-lengths, 
the sum of which presents to the eye white light or light to which the eye can 
react harmoniously and rationally. The nature of the filter chosen helps diffuse 
the light to reduce glare. G. E. M. 

Increasing Light Efficiency in Projection. F. HAUSER. Filmtechnik, 6, 
December 13, 1930, pp. 1-6. Tests of the Busch Neospiegel mirror reflector for 
increasing the efficiency of the projection arc show it to be superior to the ordinary 
spherical reflectors. The newly developed reflector is claimed to overcome some 
of the objectionable properties inherent in elliptic and parabolic shapes. The 
results of tests of new large-aperture projection lenses developed by the same 
firm are given. A large number of illustrations are used which show the benefits 
obtained with the various optical trains. L. E. M. 

Testing of Sound-Picture Channels. G. F. HUTCHINS. Electronics, 2, No. 2, 
February, 1931, p. 500. In sound picture production, it is important to have a 
complete knowledge at all times of the condition of each recording channel. This 
should be tested as a matter of daily routine and this paper is concerned chiefly 
with the details of these tests. A. C. H. 

Frequency Characteristics of Optical Slits. J. P. LIVADARY. Electronics, 2, 
No. 2, February, 1931, p. 512. An analysis is made of the attenuation due to the 
finite width of the slit in sound recording. A table is included showing the 
attenuation losses as a function of frequency for slits having a width of 0.5, 1.0, 
2.0, and 3.0 mils. A. C. H. 

Sensitizing the Photo-cell. RICHARD FLEISCHER. Electronics, 2, No. 2, Febru- 
ary, 1931. The sensitizing of photo-electric cells by means of a glow discharge in 
hydrogen has been known since the time of Elster and Geitel. This sensitizing 
process produces a marked increase in sensitivity and a shift in the spectral sensi- 
tivity. The constancy of a sensitized cell depends principally upon the establish- 
ment of a condition of equilibrium between the residual gas and the photo-electric 

March, 1931] ABSTRACTS 373 

surface. Various experiments are described in the present paper which bear 
on the cause of the increase in sensitivity. A. C. H. 

Television in Color from Motion Picture Film. HERBERT E. IVES. /. Opt. Soc. 
of America, 21, January, 1931, p. 2. It is shown that the Kodacolor motion picture 
film lends itself particularly well to the solution of the problem of transmitting 
colored motion pictures over the wire or radio. A. C. H. 

A Multi-Channel Television Apparatus. HERBERT E. IVES. /. Opt. Soc. 
of America, 21, January, 1931, p. 8. An excellent summary of the fundamental 
difficulties that must be overcome before "fine-grained" television images can 
be transmitted. If a single channel is used, television signals must be sent at 
the rate of 7,000,000 per second. This would be impossible with the frequen- 
cies used at present in radio broadcasting. One solution is to use several rela- 
tively narrow frequency bands. The paper contains a description of a three- 
channel system. The multi-channel scheme has some advantage in compactness 
but, as the several circuit elements must perform uniformly, there is increasing 
difficulty as the number of channels is increased. A. C. H. 

A New Photographic Effect. FRANKLIN E. POINDEXTER. /. Opt. Soc. of 
A merica, 21, January, 1931, p. 59. It is found that the application of pressure to a 
photographic emulsion prevents the formation of a latent image to a remarkably 
large extent. This effect is of interest in connection with theories of the latent 
image. A. C. H. 

World's Theaters Wired for Sound. Mot. Pict. Daily, 29, January 24, 1931, 
p. 4. According to an approximate survey made by the Motion Picture Division 
of the U. S. Department of Commerce, 34 per cent (i.e., 19,894) of the 58,082 
motion picture theaters of the world were wired for sound as of November 1, 

1930. Charts are shown giving data for Europe, the Far East, Latin America, 
Africa, and the Near East. Data for the chief countries are as follows: U. S. 
22,731 theaters, 12,500 wired; Canada 1183, 653 wired; Great Britain 4500, 
2602 wired; Germany 5360,939 wired; France 3236,460 wired; Brazil 1600, 
125 wired; Japan 1327, 25 wired. G. E. M. 

Combination Frost Screen and Cooling System. Film Daily, 55, January 14, 

1931, p. 2. A metal screen, back of which is placed a refrigerating system, is 
a late development in theater equipment. The metal becomes covered with a 
white frost and the visual effect of this surface is said to be an improvement 
over the frosted glass screen. Fans directed on this screen, blow cool air from it 
to the audience. C. H. S. 

A Line Filament Exciter Lamp and Accompanying Slit-less Optical System for 
Sound Film Reproduction. L. DUNOYER. Tech. Cinemat., 1, November- 
December 1930, p. 43. By substituting a line filament exciter lamp for that 
using a coiled filament it is unnecessary to include a slit in the reproducer illumi- 
nation system. Reference is given in this article to the patents on a lamp having 
such a filament and a plane parallel glass side. The optical system is designed 
to correct for the astigmatism resulting from the finite thickness of the glass. 

C. E. I. 

The Artisol 75 Ampere Lamp. Tech. Cinemat., 1, November-December, 
1930, p. 44. A reflector arc lamp for motion picture projectors is announced 

374 ABSTRACTS [j. s. M. P. E. 

which is suitable for currents between 45 and 75 amperes. In order to avoid the 
risk of the arc flame reaching the glass mirror and cracking it, the flame is drawn 
slightly upward by an electromagnet. C. E. I. 

Screen Characteristics and Natural Vision. L. M. DIETERICH. Mot. Pict. 
Projectionist, IV, Jan., 1931, p. 17. A discussion of the question of screen 
proportion in relation to the natural field of view of the normal eye. The angular 
limits of unstrained binocular vision are shown in diagram form. The zone of 
comfortable seeing on such a chart is found to correspond closely to the 5 to 8 
ratio of dimensions which has been suggested as ideal for the motion picture 
screen. A. A. C. 

New Brenkert High Intensity Lamp. Mot. Pict. Projectionist, IV, Jan., 1931, 
p. 15. The design and construction of the latest Brenkert projection lamp 
are here described and its advantages are listed in detail. It is claimed to give 
unusually even illumination on screens up to a 40 foot size. A. A. C. 

New Projection Optical System. I. L. NIXON. Mot. Pict. Projectionist, 
IV, Feb., 1931, p. 13. A descriptive article on the Super Cinephor pro- 
jection lenses and condensing systems designed by the Bausch & Lomb Optical 
Company for use with wide film. The necessity for exact spacing of the con- 
denser system is emphasized. A. A. C. 

New "Ortho-Krome" Screen Development. Mot. Pict. Projectionist, IV, 
Feb., 1931, p. 21, also p. 18. This screen material is said to so regulate the amount 
of light reflected to the eye that strain and fatigue are much reduced for the 
observer. It consists of a pattern of small square pigmented areas intermingled 
with white squares in proper proportion so that the quality of the illumination 
more nearly resembles sunlight. The size of these individual squares is made 
small enough to prevent their being resolved at the normal viewing distance. 

A. A. C. 

Light Reflection Factors of Acoustical Materials. A. L. POWELL AND C. L. 
Dows. Trans. Ilium. Eng. Soc., XXV, Dec., 1930, p. 882. There is a growing 
practice of lining the ceilings and walls of interiors with sound absorbing materials. 
Many of these have relatively high light absorption, and this must be taken 
into account in the design of lighting systems. The results of tests on the re- 
flection factors of most of the types of acoustical materials in common use are 
reported. A. A. C. 

Sound Picture Equipment in U. S. S. R. M. J. MOSHONKIN. Amer. Cinema- 
tographer, XI, Dec., 1930, p. 9. Apparatus has been developed for sound recording 
and reproduction during the last four years in Russia, under the direction of 
Prof. Shorin. The principle employed is that of the single ribbon oscillograph, 
and can be applied to both variable-area and variable-density methods. The 
paper gives a general description of the apparatus and contains illustrations 
showing the assembled units. Of interest is the statement that the Soviet five- 
year plan calls for forty thousand sound picture installations. A. A. C. 

Warner Brothers' New Camera. WILLIAM STULL. Amer. Cinematographer, 
XI, Dec., 1930, p. 11. The first public showing of this new product took place at 
the October meeting of the American Society of Cinematographers; it is re- 
ported to be a distinct advance in camera design, and absolutely silent in opera- 

March, 1931] ABSTRACTS 375 

tion. The optical system is the outstanding feature of the design, the objective 
lenses being mounted on the turret in fixed mounts with the entire turret mov- 
able for focusing. The focus adjustment is observed through a prism which 
reflects up to a horizontal ground glass, and the image at this point is again 
reflected back through the finder to a binocular eyepiece at the rear of the camera. 
By the turn of a lever a second prism reflecting 25 per cent of the light may be 
substituted for the first in the finder system, allowing the operator to focus his 
lens during the operation of the camera. A. A. C. 

The Noiseless Motion Picture Camera "Cinephon." L. KUTZLEB. Kino- 
technik, 12, December 20, 1930, pp. 644-6. A camera, for which the minimum 
of noise is claimed, is constructed especially for sound work according to the 
design of Slechta of Prague. The mechanism and the pull-down are said to 
operate almost without sound. The remaining sounds, including that caused 
by the perforations of the moving film, are deadened by a double housing of 
sound-absorbing material, which increases the size and weight of the camera 
only slightly. The film magazines, mounted on the top of the camera, hold 
300 meters of film. A revolving turret of four lenses is provided. A prism 
and 7x magnifier permit focusing on a ground glass in the film aperture without 
opening the camera. A scale indicating the sector shutter opening and a control 
handle for the automatic dissolve mechanism are found on the back of the camera. 
A lamp is mounted in the camera for exposing the edge of the film outside the per- 
forations to aid in synchronizing the picture with the sound record. M. W. S. 

Projectophone System. D. VON MIHALY. Filmtechnik, 6, December 13, 1930, 
pp. 6-9. A system of reproducing sound on film known as the Projectophone is 
sponsored by Mihaly, who devised it. The system comprises the customary 
necessary units, but has in addition a long focal length lens by means of which 
the sound record can be projected to the photo-electric cell located outside the 
projection room. This method of projecting the sound record permits the 
photo-electric cell and amplifier to be located together, at a distance from the 
projector and other electrical equipment. It is suggested that the principle 
employed in the Mihaly system may be of value for the projection of home 
movies. L. E. M. 

European Sound-on-Disk Equipment Data. P. HART. Filmtechnick, 6, 
December 13, 1930, pp. 9-10. Data on methods of coupling, synchronizing, 
electrical equipment, etc., characteristic of the various European makes ot sound- 
on-disk systems are presented compactly in the form of tables. L. E. M. 

Television Process. The Film Daily, 55, January 18, 1931, p. 7. This 
process, including a newly developed screen, is claimed to make possible the 
projection of pictures onto an ordinary full-sized screen, to televise people and 
objects illuminated only by arc light or daylight, and to show an unlimited amount 
of detail in the picture. The principle of the process is to divide the subject into 
zones and televise each zone from a separate amplifier and through its own line 
to the receiver. A system of revolving mirrors is used to convey the light from 
the receiver to the screen. Any number of zones can be used, each necessitating 
a separate amplifier and receiving set. The method is a modification of the Baird 
method of television. C. H. S. 

Noiseless Recording. H. C. SILENT. Ex. Herald-World, 101, December 27, 

376 ABSTRACTS [J. S. M. P. E. 

1930, p. 30. A dark print of a variable density sound record gives low volume 
reproduction and low ground noise, but as the print is made lighter, the ground 
noise level increases. A new auxiliary electrical circuit permits control of re- 
cording so that the volume is reduced for low volume sounds and automatically 
increased as the volume rises. The ribbons of the light valve have been set 
0.001 inch apart in the past for recording and the strongest currents just bring 
them together. For weak currents the space was greater than necessary. Ac- 
cording to the new system, the ribbons are set closer and the space is widened 
automatically to accommodate loud volume sounds. Thus the amount of light 
which reaches the film or the reproducing photo-electric cell has been unaltered 
even though the total amount has been decreased. No volume distortion on 
reproduction, therefore, is introduced. The device has been arranged so that 
photographic overload and light valve overload occur simultaneously when the 
set is adjusted for normal recording. Ground noise is claimed to have been re- 
duced ten db. under commercial tests, and sounds previously completely ob- 
scured by ground noise may now be recorded and reproduced satisfactorily. 

G. E. M. 

New Type Microphone. Mot. Pict. Herald, 102, Jan. 24, 1931. p. 42. A 
corrugated aluminum ribbon 0.0001 inch thick, 3 /ie inch wide, and 2 inches long 
is placed between the poles of an electromagnet. Minute changes in air pressure 
produced by sound waves cause the ribbon to vibrate and set up an electric 
current, which is led to a transformer connected to a vacuum tube amplifier of 
the conventional type. The microphone is contained within a perforated box 
fastened to the base of an amplifier. A feature of the new microphone is its 
directional pick-up characteristics, sounds normal to the face being reproduced 
completely whereas the reception in the plane of the face is zero. Thus, if the 
camera is placed in this plane, any noise coming from it, is not recorded. 

G. E. M. 


Carrigan, J. B. MacNair, W. A. 

Cook, A. A. Matthews, G. E. 

Crabtree, J. T. McNicol, D. 

Hardy, A. C. Meulendyke, C. E. 

Herriot, W. Muehler, L. E. 

Irby, F. S. Schwingel, C. H. 

Ives, C. E. Seymour, M. W. 

Loveland, R. P. Tuttle, C. 

Weyerts, W. 

March, 1931] ABSTRACTS 377 


1,753,530. Sound Recording Apparatus. F. H. OWENS. April 8, 1930. 
Relates to an electromagnetically operated light slit in which a constant light 
source is provided in optical relation to a film in a sound recording system. 
The light slit consists of a pair of slidable shutter members, each being con- 
nected to separate diaphragms which are electromagnetically controlled from 
a voice control circuit. The diaphragms are adjustably connected with each 
of the shutter members constituting the light slit. Operation of the voice 
control circuit controls the position of the shutters and the exposure of the light- 
sensitive film with respect to the light source. 

1,758,221. Motion Picture Camera. H. A. DEVRY. May 13, 1930. A 
motion picture camera in which the operating parts are compactly arranged 
within a portable case for utilizing standard size film, the parts being readily 
accessible for threading of the film and the inspection of the parts when the case 
is open. The camera is provided with a hinged side which may be swung out- 
wardly from the casing to permit access to the supply and take-up spools, each 
of which may be removed end-wise from the casing. 

The intermittent film driving mechanism, the shutter mechanism, and the 
film guide are all arranged to be accessible from one side of the casing when the 
hinged cover is swung open. 

1,759,914. Producing Films for Color Cinematography. A. PILNY. May 27, 
1930. A method of producing film strips for cinematography, comprises splitting 
a series of images rectangularly and projecting them onto longitudinal parallel 
portions of a film strip by folding the strip longitudinally at right angles to unite 
the portions of the film for receiving the partial images. A film is employed in 
the making of the color motion pictures which is of double width and which is 
folded longitudinally upon itself. Partial pictures are produced in symmetrical 
arrangement to each other on the folded film, enabling a simple production of a 
positive color film by placing a film consisting of a colored layer impervious to 
light between the emulsion coatings on the folded film. 

1,774,097. Pocket Cinematograph. P. HAUSER AND EDUARD PROBST. 
August 26, 1930. Relates to a diminutive motion picture projector which may 
be carried in a pocket. The projector is said to have a dimension of 2 in. by 
4 in. by 1 inch. Two side plates are provided between which the film reels 
are journaled. One of the reels is driven through a hand crank and a gear 
system. The casing of the projector includes a lens system and a step-by-step 
movement mechanism for successively exposing the film to a light source which 
may be connected through a flexible cord with any suitable source of power. 
The particular feature of the invention is the telescopic portion of the case which 
may be telescopically dropped down from the casing to receive the end of the 
film as the projection process continues. 

1,778,351. Motion Picture Projector Using Pictures on a Disk. L. W. 
BOWEN. October 14, 1930. A motion picture machine wherein a series of pic- 
tures are arranged spirally and radially on a transparent plate or disk film. 
The film is given both a rectilinear and an intermittent rotary movement in the 
course of projection of the pictures. The apparatus is housed inside a casing 
within which there is a carriage mounted for rotatively supporting a disk film. 

378 ABSTRACTS [j. s. M. P. E. 

A system of gears connected through a drive shaft enable rotary motion to be 
transmitted to the disk film. Rectilinear motion may be imparted to the car- 
riage whereby a spiral record on the film may be reproduced through an optical 
system by the advancing of the film at the end of each complete revolution 

1,780,311. Home Motion Picture Projector. A. PAPO AND A. GENTILINI. 
November 4, 1930. Relates to a home projector for motion picture film in 
which an optical system and reflector are mounted on a carriage and movable 
in a line normal to the optical axis of the projecting machine. The reciprocatory 
carriage contains a reflecting prism adapted to be aligned with the light source 
for directing the light rays through a projecting lens upon an exhibiting screen. 
The carriage is reciprocated by the engagement of a pawl with the film. A 
shutter is actuated as the carriage is reciprocated by engagement of the pawl 
with the film, thereby obscuring the picture during the return movement of the 
carriage under action of the spring. The reciprocating carriage, containing the 
shutter mechanism, a prism, and a reflecting lens, eliminates the usual con- 
struction of rotary shutter and renders the construction of the machine more 
compact for home operation. 

1,781,945. Alignment Guide for Sound Track on Motion Picture Projector. 
T. W. CASE. Assigned to Case Research Laboratory, Inc. November 18, 
1930. Covers a guide for film having a sound track thereon where the film rides 
over a body portion of the guide and is held in contact therewith so that the 
sound record on the film registers with a longitudinal channel in the guide at 
one side of the picture, record on the film. The shoe which maintains the film 
against the guide is spring-pressed and is designed to eliminate wear or scraping 
of the film while maintaining the film in accurate alignment so that the sound 
track is directly in alignment with the channel portion of the guide through 
which light rays pass to the sound portion of the film. 

1,783,169. Means for Winding Endless Cinematograph Films. M. HARPER. 
November 25, 1930. Relates to a drum for the winding of endless films. The 
drum comprises two plates, one made in the form of a flat ring and the other 
solid, with rollers carried around the periphery of the flat ring and the plate. 
There is an aperture in the plate in which a roller is mounted for the passage 
of the beginning of the film as it is unwound from the lower layer on the peri- 
pheral rollers. The entire rotatable drum is mounted in a horizontal position 
adjacent to the projection machine and adjusted to continuously take the film 
from the center of the reel and restore the film after projection to the exterior 
of the reel. 

1,783,399. Binocular Motion Picture Camera. A. AMES, JR. December 2, 
1930. Relates to a method of and apparatus for making motion pictures of 
the type in which the screen image is binocular in the sense of containing a 
composition of images from two different points-of-view representative of two- 
eyed vision. The invention is particularly concerned with obtaining the effect 
of retinal rivalry, so-called characteristic of normal human binocular vision. 
Images are formed from different points-of-view and different parts of a sensi- 
tive film successively exposed during separate exposures, following each other 
at intervals within the time of the persistence of vision of each of these images 
severally. Thereafter the successively different parts of the film are exposed 

March, 1931 ] ABSTRACTS 379 

to the images simultaneously. The resultant effect is that the form of the 
object observed on the screen appears real and relative distances are given 
with effect of depth in the picture. 

1,784,138. Nonstop Motion Picture Projector. C. M. GOTTSCHAU. Decem- 
ber 9, 1930. A motion picture projector of the type having a continuous film 
without the necessity of rewinding of the film prior to a subsequent exhibition. 
The driving mechanism for the film includes a running drive for the reel which is 
adapted to slip under a predetermined resistance. A starting drive is provided 
which is more positive than the running drive. Means are provided for auto- 
matically disconnecting the starting drive after a predetermined movement of 
the reel. 

1,784,515. Binocular Nonstop Motion Picture Camera. H. K. FAIRALL. 
Assigned to Multicolor, Ltd. December 9, 1930. A device for intermittently 
advancing the film in a motion picture camera. The movement comprises a 
pair of cranks each adapted to directly support and operate the film advancing 
means. The cranks operate simultaneously to shift the film advancing means 
in step-by-step movement at uniform speed for each frame of the picture. 

1,785,336. Stereoscopic Motion Picture Film and Method of Making. J. 
BURKHARDT. Assigned to Third Dimension Pictures, Inc. December 16, 
1930. A motion picture film for securing relief or stereopticon effect in repro- 
duction. The pictures are printed in miniature in pairs disposed transversely 
on the film. The film is of standard width and stereoscopic or third dimension 
effects or illusions are obtained by the pairs of pictures. The background of 
each pair has thereon a mask of the foreground picture of the pair. 

1.786.025. Optical System for Reproducing Sound Records. F. H. OWENS. 
December 23, 1930. Covers a system for subjecting a film to a beam of light 
where the gates through which the light passes may be removed out of contact 
with the film. The movement of a film directly against the usual slit results 
in the accumulation of dirt and other foreign matter in the slit which clogs it 
and interferes with the function of the optical system. 

An optical system is used which produces a converging beam of light, the focus 
of which passes through a slit located substantially at the focus of the light 
beam, the beam diverging from the slit for illuminating a film which is spaced 
from the slit. There is a second slit on the other side of the film for producing 
from the light beam a beam of light of reduced divergence which is focused upon 
a light-sensitive cell. The slits which control the passage of light from the 
source upon the light-sensitive cell are disposed in spacial relation to the film 
and do not contact with the film in the course of the movement of film past 
the slits. 

1.786.026. Lamp House for Sound Picture Apparatus. F. H. OWENS. 
December 23, 1930. A lamp housing for the light source in the talking picture 
attachment for a motion picture projecting machine. The lamp housing is 
constructed with a pair of integrally connected sides through one of which the 
optical system extends and on the other of which the light source is supported 
in alignment with the optical system. A hinged structure comprising the two 
remaining sides of the housing provides a support for the cathode control rheo- 
stat, the required meters, the control switches for the light source. The lamp 
housing may be compactly mounted with respect to the parts of the motion 

380 ABSTRACTS [j. s. M. P. E. 

picture projector, and affords a convenient means for adjusting or repairing 
of elements associated with the light source. 

1,786,027. Reproducing a Plurality of Photographic Sound Records on One 
Film. F. H. OWENS. December 23, 1930. A sound reproducing system 
utilizing a film which carries a multiplicity of sound records. A single light 
source is provided for all of the parallel extending sound channels on the film. 
There are separate light slits disposed in alignment with the channels recorded 
on the film and aligned with independent photo-electric cells so that all of 
the sound channels recorded on the film may be reproduced simultaneously. One 
sound channel may bear the record of one musical instrument while the other 
sound channels may bear the records of other musical instruments which have 
been officially recorded over different frequency ranges. Provision is made 
for adjusting the sides of each of the light slits by shutter members whereby the 
relative amount of modulated light received by each of the photo-cells may be 
adjustably regulated. 

1,786,274. Synchronous Motion Picture and Sound Reproduction. F. VON 
MADALER. Assigned to National Vision-Tone Corporation. December 23, 
1930. Discloses the design of a talking picture apparatus having sprockets 
and film feeding mechanism spaced at predetermined intervals and adapted 
to receive a film having markings thereon at spaced intervals to indicate the 
position in which the film must be mounted for initially feeding the film in proper 
position through the projecting machine. 

1,786,301. Sound Recording and Reproducing Apparatus Utilizing a Film 
Having a Plurality of Sound Records. C. L. HEISLER. December 23, 1930. 
An apparatus for recording and reproducing sound from film where the sound 
is recorded successively in a plurality of tracks on the film. The film is moved 
longitudinally in opposite directions at substantially uniform speed. A narrow 
beam of light is projected on the film and the film-supporting device shifted 
transversely in order to effect reproduction or recording from the different 
sound channels. 

1,786,368. Synchronizing Photography and Sound Recording. J. J. F. 
STOCK. December 23, 1930. A camera for coordinating the taking of pictures 
with the recording of music. A film- winding shaft is provided in the camera. 
A device for feeding equal lengths of film through the camera during equal 
intervals of time is provided, comprising a continuous drive for the film-winding 
shaft. A friction clutch is connected between the drive and the shaft on which 
a pawl and ratchet arrangement is provided. An electro-magnet is arranged 
for actuating the pawl. The clockwork mechanism is provided for energizing 
the electromagnetic means in definite timed relation for operating the pawl 
in predetermined order for controlling the operation of the film- winding shaft. 
The speed at which the film is advanced is automatically regulated in accordance 
with the production of music. 

1,787,023. Camera and Method of Special Process Photography. J. F. 
SEITZ. December 30, 1930. Covers a method of making mats by exposing a 
film to two component parts of a picture simultaneously, one part photographing 
on one face, and the other on the other face of the emulsion or film. The film 
is developed and the picture projected on a screen and utilized in the making 
of a mat. In this manner photographs may be taken through different lenses 

March, 1931] ABSTRACTS 381 

[ on the same film or plate at the same time and the different pictures may be 
superimposed on one or the other or may be matted separately and in a manner 
complementary to each other so that when brought together on the same film 
they will make a composite picture. 

1,787,426. Compound Ventilating Shutter. A. DINA. Assigned to Inter- 
national Projector Corporation. January 6, 1931. A rotatable shutter for 
a motion picture projection machine which is arranged with spaced separate 
fixed portions, the leading one of which is disposed in the plane of rotation of 
the blade and the trailing one of which is disposed at an angle to the plane of 
rotation of the blade, the adjacent edges of the said portions overlapping to 
prevent the transmission of light. The shutter provides a ventilating and 
cooling device for the projection head of the motion picture machine, while 
at the same time the effective width of the blade in the plane of rotation is un- 
changed so that the light-cutting capacity of the blade- is unchanged regardless 
of the variability of the angle of the portions of the shutter. The intervening 
spaces in the shutter are effectively shadowed to prevent the transmission of light 
during the cutting movement of the blade. 

1,788,740. Method of Making Composite Pictures. R. J. POMEROY. As- 
signed one-half to Paramount Publix Corporation. January 13, 1931. A 
color motion picture system in which two component images are produced. 
One component is illuminated with light of a selected color before a ground 
illuminated with light of a color having a minus relation to the selected color. 
The other component is illuminated selectively with light from the ground. 
Different parts of a fresh actinic film are exposed selectively to the second- 
mentioned illuminated component and to the illuminated first-mentioned com- 
ponent in lights of their respective colors. This invention provides a method 
whereby the scheme of complementary or distinctive illumination colors (colors 
that may be described as having a minus relation to each other) may be. utilized 
for the production of composite pictures without the necessity of preparing a 
special photographic transparency in one of said colors, whereby an ordinary 
black and white photograph may be utilized in the place of such a color trans- 

1,788,808. Motion Picture Apparatus Using a Disk instead of a Film. S. F. 
STEIN. January 13, 1931. Relates to a projection machine wherein the film 
is in the form of a disk having pictures arranged in circular paths around the 
circumference thereof. A multiplicity of light beams are projected through the 
rotatable picture carrier for projecting pictures upon the same screen. The 
movement of the rotatable picture carrier is coordinated with the movement 
of a phonograph. Different pictures pertaining to the same event may be 
superimposed upon each other on the same screen or the pictures may be pro- 
jected in succession from the circular record on the picture carrier. 

1,789,607. Device for Projecting a Film Having a Plurality of Sound Records. 
J. H. STEURER. January 20, 1931. Relates to a sound reproducer consisting of 
a film-moving apparatus which is adapted to reversibly feed a film first in one 
direction and then in the opposite direction for the reproduction of sound from 
a multiple-track sound record on the film. The shifting apparatus which changes 
the position of the light gate transversely with respect to the film is operated 
automatically to bring the light gate into alignment successively with the separate 


sound tracks whenever the feed of the film is reversed, so as to form a practically 
continuous operation from one sound track to the next. The inventor describes 
the apparatus as the "talking book," as a long sound record which may be in- 
struction from a text-book may be recorded and reproduced as the film moves 
first in one direction and then in the opposite direction. 

1,790,232. Motion Picture Camera Having a Movable Lens System. ROLLA 
T. FLORA. January 27, 1931. A motion picture camera having a movable 
lens system controlled by an operating device by which short-focal, telephoto, 
or any intermediate foca.1 characteristics with respect to a given focal plane, may 
be obtained quickly. 

The camera is set up to take a long shot and while the film is being exposed 
the lenses are moved to cause the gradual magnification or increase of linear 
dimensions of the image on the film, thus giving the effect of a gradual change 
from a long shot to a close-up. Or, a long shot may be made and then exposure of 
the film stopped until the lenses have been moved to such a position that the 
image on the film will be magnified to a predetermined degree. 

The shifting of the lens system may be rapidly effected by movement of an 
oscillatory arm connected through a link with the lens mount. 


Elements of Optics. JOSEPH VALASEK, PH.D. McGraw-Hill Book Company, 
Inc., New York, N. Y., 1928, XIII + 215 pp., $2.00. The author, associate pro- 
fessor of physics at the University of Minnesota, states in the preface that this book 
was" written to fill the need for a modern text-book of optics for a beginning course 
of college grade extending over three months." Within the short space of 191 
pages of text, he has compressed a certain amount of information on an astonish- 
ing number of topics covering the entire realm of optics. There are fourteen 
chapters with chapter-headings as follows: (1) Light and Its Propagation; 
(2) Photometry; (3) Velocity of Light; (4) The Wave Theory of Light; 
(5) Reflection; (6) Refraction; (7) Lenses; (8) Optical Instruments; (9) 
Color; (10) Interference; (11) Diffraction; (12) Double Refraction and 
Polarization; (13) Radiation; and (14) The Theory of Relativity. The chapter 
on lenses contains 16 pages and the chapter on optical instruments 14 pages; 
it is obvious that this amount of space cannot permit a discussion of these 
subjects in sufficient detail to meet the needs of anyone who requires more than 
the most elementary principles. As the basis of a preliminary course in optics, 
designed to give a student in physics the basic principles of the subject and 
some comprehension of the range of the subject-matter content of the science, 
the book is admirable. As a reference book for the projectionist or cinema- 
tographer, it would generally be disappointing because of the meagerness of the 
information presented on the majority of subjects in which he would most likely 
be interested. It can be recommended, however, as a supplement to other books 
dealing more adequately with geometrical optics, lenses, and optical instruments 
as a source of very well presented and easily comprehended information on such 
subjects as the nature of light, interference, diffraction, etc., concerning which 
the average projectionist or cinematographer may feel some interest but not 
enough to justify him in an attempt to read the more elaborate treatises dealing 
with these subjects. W. B. RAYTON 

Basic Photography. Training Manual No. 2170-5, U. S. Army Air Corps. 
Government Printing Office, Washington, D. C. This text-book on standard photo- 
graphic practice, issued primarily for the training of officers and enlisted men, con- 
tains much valuable information of interest to the still photographer and tech- 
nician. The subject matter includes a description of cameras and equipment, 
negative exposure and development, printing, enlarging, and the making of 
lantern slides. The use of filters is treated in connection with various types of 
reproduction problems. An adequate index adds to the usefulness of the volume. 


Panchromatic Photography. F. H. WILDING. Photo- Miniature No. 203, 
17, December, 1930, pp. 551-604, Tennant & Ward, New York, N. Y. In view 
of the increased use being made of panchromatic materials, this handbook should 
find a useful place in the library of most cameramen and commercial photog- 
raphers. It presents in clear, concise language the fundamental principles under- 


384 BOOK REVIEWS [J. S. M. P. E. 

lying the use of panchromatic films or plates and the application of color filters. 
The characteristics of various illuminants such as incandescent tungsten, carbon 
arc, sun arc, flame arc, mercury vapor, and neon are dealt with briefly, although 
the author's practical knowledge concerning the application of the last two 
materials appears somewhat meager. A comprehensive section of the booklet 
discusses the composition and use of color filters, which are classified under their 
applications as taking, viewing, and safelight filters. The use of desensitizers 
is treated, and mention is made of a plate backed with a desensitizing material 
which dissolves in the developer and acts on the plate during the early stage 
of development. Consideration is given in a closing section to the use of pan- 
chromatic materials in several fields, landscape, portraiture, telephotography, 
aerial photography, etc. The manuscript was prepared, unfortunately, before 
the introduction of certain high-speed panchromatic materials, a discussion of the 
properties and uses of which would have made a valuable addition. 


The Talkies. JOHN SCOTLAND. Crosby Lockwood and Son, London (The 
Industrial Book Co., Inc., New York), 1931, 194 pp. A popular and elementary 
account of the history and present technic of sound motion pictures, written 
primarily from a British view point. The author briefly traces the development 
of the art, beginning with the early experiments of Edison in 1888, and credits 
Eugene Lauste with "the first development of talkies as we know them today" 
in England twenty-three years ago. References to the early British talking 
picture productions by Cecil M. Hepworth are given. The remainder of the book 
is devoted to a description of the photographic and sound recording apparatus 
used in making sound pictures, with considerable emphasis on British equipment, 
and to a general review of the apparatus and problems of sound reproduction 
in theaters. The author next deals with color pictures, and closes with a chapter 
giving the reactions of various American stars to talkies as opposed to silent 
pictures. The book is of elementary character, suitable for reading by laymen 
who have an amateur interest in the technic of the art. It is entertainingly 
written, but its comparative lack of reference to American practice would render 
it of greater interest to the British rather than the American reader. 


The Talkies. ARTHUR EDWIN KROWS. Henry Holt & Co., New York, N. Y., 
1930, $2.00. Mr. Krows has attempted in this volume to present a summary 
of the history, mechanical technic, status as an art, and probable future of the 
motion picture, embracing both the silent and sound phases of the medium. 
The exposition of the artistic considerations is most praiseworthy, involving as 
it does the duties of the scenarist, director, film editor, and the difficulties com- 
monly encountered by each. The evolution of the existing scheme of production 
is clearly shown, together with an appreciation of the economic factors which 
beset all departments of the film industry in attempting to elevate the motion 
picture to higher artistic levels. The history of picture and sound, preceding 
their union into the sound picture, is told in great detail, perhaps too much detail 
for the lay reader. That section which describes recording and photographic 
technic is not too satisfactory from the standpoint of the engineer. There are a 
number of glaring inaccuracies which could have been eliminated by submission 
to technical men for proof-reading. Though written for the layman, there is 

March, 1931] BOOK REVIEWS 385 

no justification for creating misconceptions in the mind of the uninitiated. 
The excellence of this work in considering the dramatic factors is marred by the 
deficiencies in the technical section J. L. CASS 

Photography Theory and Practice. L. P. CLERC. Edited by George E. 
Brown. Pitman & Sons, Ltd., London, 1930, 556 pp. This voluminous text, which 
is an English edition of La Technique, Photographique, published as two volumes in 
1926, represents a compilation of material giving the fundamental facts of photog- 
raphy. Yet no attempt has been made to make the work encyclopedic, or to 
load it down with references; rather it has been the purpose "... to bring into 
one volume as complete a treatise as possible on modern working methods and 
apparatus ..." For more than thirty years, the author's professional duties 
have necessitated his reading a good share of the literature published on photog- 
raphy as well as to conduct experiments in many fields of photographic work. 
He is thus particularly well equipped for the task which he so admirably has 
completed. The volume has been written to emphasize the practical aspect of 
photography and therefore should prove a valuable addition to the library of 
every serious photographic worker. The first fifteen chapters deal with light, 
perspective, optical systems, diaphragms, shutters, lenses, types of cameras, 
and the negative. Subject matter taken up in the following ten chapters is 
related to the properties of negative materials, darkroom design and equipment, 
chemicals, lighting, and focusing. Then, in ten succeeding chapters, the author 
discusses exposure, development, fixing, washing, drying, negative failures, 
reversal processes, after-treatment, classification, and storage. Concluding the 
treatment of negative materials, the next five chapters are devoted to printing. 
The last 175 pages are reserved for a consideration of special subjects including, 
among others, pigment processes, trimming and mounting prints, copying, 
enlarging, lantern slide making, color photography, an outline of cinematog- 
raphy, photo-mechanical processes, and radiography. An excellent chapter 
is included on the theory and practice of stereoscopy. G. E. MATTHEWS. 



J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westhighouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 
Los Angeles, Calif. 

M. W. PALMER, Paramount Publix Corp., 35-11, 35th Ave., Long Island City, 

N. Y. 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 





W. V. D. KELLEY, Chairman 










W. C. KUNZMANN, Chairman 

C, L. GREGORY, Chairman 



Membership and Subscription 
H. T. COWLING, Chairman 




O. M. GLUNT, Chairman 










D. McNicoL 

G. E. MATTHEWS, Chairman 











[j. S. M. P. E. 

Projection Practice 
H. RUBIN, Chairman 




Projection Theory 
W. B. RAYTON, Chairman 



W. WHITMORE, Chairman 




H. B. SANTEE, Chairman 

Standards and Nomenclature 
A. C. HARDY, Chairman 



Studio Lighting 
M. W. PALMER, Chairman 


Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 
M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

D. MACKENZIE, Chairman G. MITCHELL, Manager 

E. HUSE, Secretary H. C. SILENT, Manager 

L. E. CLARK, Treasurer 












Crabtree, J. L: See January, 1931, issue of JOURNAL. 

Dutton, W. P.: B.S. in E.E., Union College, 1924; radio operator, Radio 
Corporation of America, 1921-22; broadcast station operator at WGY, General 
Electric Company, 1922-24; radio engineering department, development and 
design of speech input and transmitting equipment for broadcasting stations, 
General Electric Company, 1924-28; radio engineering department, develop- 
ment and design of Photophone recording equipment, General Electric Company, 
1928-30; engineering department, RCA Victor Company, Inc., 1930 to date. 

Glunt, Omer M.: Born February 4, 1884, at Union City, Ohio. M.E. in 
E.E., Ohio State University, 1906; Western Electric Company, 1906-25; in 
charge of development of special communicating equipment and of commercial 
radio and sound picture apparatus and systems, Bell Telephone Laboratories, 
1925 to date. 

Graham, Frank H.: Born September 6, 1889, at Landisburg, Pa. B.S. in 
E.E., Pennsylvania State College, 1914; engineering department, vacuum tube 
and transmission research, Western Electric Company, 1915-25; acoustical 
and hearing research, Bell Telephone Laboratories, 1925-29; engineering depart- 
ment, theater reproducing systems, Electrical Research Products, Inc., 1929 to 

Hardy, A. C.: A.B., University of California, 1917; M.S., University of 
California, 1919; commanding officer, 23rd Photographic Section, A. E. F., 
France, 1918; physicist, Eastman Kodak Company 1920-21; assistant professor 
of Optics and Photography, Massachusetts Institute of Technology, 1922-28; 
associate professor of Optics and Photography, Massachusetts Institute of 
Technology, 1928 to date. Fellow, American Academy of Arts and Sciences; 
American Physical Society; Member, American Association for the Advance- 
ment of Science; Optical Society of America; Royal Photographic Society. 

Ives, Herbert E.: B.S., University of Pennsylvania, 1905; Ph.D., Johns 
Hopkins, 1908; assistant physicist, Bureau of Standards, 1908-09; physicist, 
Nela Research Laboratory, 1909-12; physicist, United Gas Improvement Com- 
pany, 1912-18; U. S. Army Air Service, 1918-19; research engineer, Western 
Electric Company and Bell Telephone Laboratories, 1919 to date. 

Lyford, E. B.: Born June 3, 1903, at Bridgeport, Conn. B.S., Wesleyan 
University; sound engineer, Pathe Studios, 1929; engineer, recording division, 
RCA Photophone, Inc., 1930 to date. 

Matthews, G. E.: See February, 1931, issue of JOURNAL. 

Morrison, C. E.: Born February 19, 1896, at London, England. A.B., 
University of Rochester, 1923; A.M., 1925; Scientific Bureau, Bausch & Lomb 



Optical Co., 1914-19; instructor in Physics, University of Rochester, 1923-25; 
assistant in Vital Economics, 1925-27; biophysicist, Research Laboratories, 
Eastman Kodak Co., 1927-28; Eastman Teaching Films, Inc., 1928 to date. 

Read, Sidney, Jr.: B.S. in E.E., University of California, 1926; student 
engineer, General Electric Company, 1926-28; radio engineering department, 
test and factory engineering on radio receivers, General Electric Company, 
1928-29 ; radio engineering department, development and design of Photophone 
recording equipment, General Electric Company, 1929-30; engineering depart- 
ment, RCA Victor Company, Inc., 1930 to date. 

Robillard, P. M.: Born January 30, 1897, at Ottawa, Canada. Communi- 
cation division, Radio Corporation of America, 1920-28; recording division, 
development and maintenance of portable and location equipment, RCA 
Photophone, Inc., 1928 to date. 

Ross, John Franklin.: Born June 19, 1900, Guinda, California. Graduated 
from the University of Michigan with the following degrees: B.S. (Chem.), 1921; 
M.S. (Chem.), 1922; Ph.D., 1924. Teaching assistant in analytical chemistry, 
University of Michigan, 1920-21; DuPont Fellow in Chemistry, 1921-24; re- 
search chemist in photographic chemistry department, Eastman Kodak Com- 
pany, Rochester, New York, 1925-29; director of analytical laboratories of the 
J. T. Baker Chemical Company, Phillipsburg, N. J., 1929 to date. 

Schlenker, Vesper A.: B.S., University of Chicago, 1919; meteorological 
section, Signal Corps, A. E. F., 1917-19; instructor in physics, Culver Military 
Academy, 1919-20; Massachusetts Institute of Technology, 1920-21; graduate, 
Officers Field Artillery School, U. S. Army, 1922; graduate, Officers Signal School, 
U. S. Army, 1923; engineering department, Western Electric Company, 1923-25; 
supervisor, special electrical and acoustical research, Bell Telephone Labora- 
tories, 1925-27; acoustical research and development, Vitaphone Corporation, 
1929-31. Consulting acoustical engineer, 1931 to date. 

Shea, Timothy E.: S.M., Massachusetts Institute of Technology, 1919; 
instructor in electrical engineering and physics, 1918-20; manufacturing de- 
partment, Western Electric Company, 1920-21; engineering department, 
Western Electric Company, 1921-24; development of sound picture equipment, 
public address systems, and similar apparatus, Bell Telephone Laboratories, 
1925 to date. 

Wolferz, Alfred H.: B.S., Cooper Union; design and development of elec- 
trical measuring instruments, Weston Electrical Instrument Corporation. 



The Spring Convention. Full details concerning three alternative 
railroad routes to Hollywood have been circulated by the Arrange- 
ments Committee. Extra copies can be secured from the General 
Office. The Board of Governors has voted to extend the convention 
over a period of five days so as to allow ample time for sightseeing 
and visits to studios. 

Headquarters will be at the Roosevelt Hotel but the technical 
sessions will be held at the American Legion Auditorium. The 
Society is greatly indebted to the American Legion for kindly 
donating the use of their headquarters for our convention. 

Arrangements are being made for an exhibition of newly- 
developed motion picture apparatus during the Spring Convention in 
order to better acquaint the members with the newly-devised tools 
which may be of value to them. This will not be of the same nature 
as the usual trade exhibit. There will be no booths, although each 
exhibit will be allotted definite space by the Exhibits Committee and 
all exhibits will be arranged in one large room. The following 
regulations will apply: 

(1) The apparatus to be exhibited must be new or have been 
developed or improved within the past 12 months. 

(2) No pamphlets or advertising literature will be permitted. 

(3) Each exhibitor will be permitted to display one small card 
giving the name of the manufacturing concern and each piece of 
equipment shall be labeled with a plain label which shall not include 
the name of the manufacturer. 

(4) A technical expert capable of explaining the technical 
features of the apparatus exhibited must be present during the 
period of the exhibition. 

(5) The hours of the exhibition will be determined by the 
Apparatus Exhibits Committee and the exhibits will be closed dur- 
ing the papers sessions. 

(6) All exhibition space will be furnished gratis. 

(7) The apparatus to be exhibited will be censored by the 
Apparatus Exhibits Committee in order to make certain that this is 
essentially new as described under item (l). 

Please make requests for space to Mr, Sylvan Harris, Editor- 


Manager of the Society, Room 701, 33 West 42nd Street, New York, 
N. Y., stating the number and nature of the items to be exhibited. 

The Journal. Members are reminded that papers can be sub- 
mitted for publication in the JOURNAL without necessarily having 
been presented at the semi-annual conventions. All members are 
urged to prepare papers and to suggest possible subjects and authors 
to the Editor of the JOURNAL. 

Now that the wave of inventive progress which accompanied the 
introduction of sound has subsided, there is a tendency for the supply 
of good technical papers to decrease, and greater effort on the part 
of all members will be necessary in order to maintain the high 
technical standing of our publication. 

The Board of Governors has approved the addition of two new 
sections to the JOURNAL, one of which will deal with new apparatus, 
and the other with announcements concerning technical literature 
distributed by manufacturers. The apparatus section is for the 
purpose of acquainting readers of the JOURNAL with new motion 
picture apparatus which has been developed or improved within the 
past 12 months. Manufacturers and inventors are invited to submit 
technical details to the Editor of the JOURNAL. These will then be 
referred to a Board of Abstractors for review. 

To date, no letters have been received for the Open Forum. 
Each member should endeavor to offer suggestions for ways and 
means of increasing the usefulness of the Society to the industry. 

New' York Section. At a meeting held at the Westinghouse 
Lighting Institute, Grand Central Palace, New York, N. Y., on 
January 23, 1931, Mr. C. E. Baer, of Eastman Teaching Films, Inc., 
delivered an address on "Visual Aids in Education" which was 
accompanied by a demonstration of outstanding examples of films 
for educational purposes. An interesting discussion followed. 

Pacific Coast Section. At a meeting held January 22, 1931, the 
following officers were elected: 

Mr. Donald MacKenzie, Chairman 
Mr. Emery Huse, Secretary 
Mr. L. E. Clark, Treasurer 
Mr. H. C. Silent, Manager 
Mr. G. Mitchell, Manager 

The new officers are making extensive preparations for the Spring 


Papers for Spring Convention. In the February issue of the 
JOURNAL the Papers Committee announced a plan which will be 
followed in connection with papers intended for presentation at the 
Hollywood Convention, May 25th to 29th, inclusive. This plan re- 
quires that papers must be submitted to the Society by April 1st. 
The response so far, in actual papers submitted, has been small and 
not very many members have come forward with information 
as to papers which they propose to present. 

It is earnestly requested by the Papers Committee that all members 
proposing to offer papers at the Convention inform the Committee or 
the Editor-Manager at the earliest possible date, giving the name of 
the author and the title of the paper in each case. This will greatly 
assist in laying plans for the papers programs at the Convention. 

It is felt that engineers are prone to assume that engineers in 
branches of the industry other than their own have a greater knowl- 
edge of specialized subjects than they actually have. It is felt that 
material exists for many worth-while papers which the Society is not 
now getting because engineers do not put themselves mentally in the 
place of their readers. It is suggested that members of the Society 
give this thought consideration, and consider broadly whether they 
do not have material for good papers which would be of real interest 
to the Society. 

In the case of authors who do not expect to attend the Convention 
but want to have papers presented, the Committee will arrange to 
have the papers presented by competent members of the Society. 

Chicago Section. At a meeting held at the Webster Hotel, 
Chicago, 111., January 8, 1931, Mr. R. F. Mitchell delivered a paper 
entitled 'Notes on Color Cinematography of Today." This paper 
described several additive color processes such as Kodacolor, the 
Gaumont process, and Kinemacolor. The subtractive processes 
described included Prizma, Technicolor, and bi-pack methods. In 
the last-named processes two films are run simultaneously through 
the camera, emulsion to emulsion. The front film is orthochromatic 
and contains a red layer over the emulsion so that the rear film 
records only a red impression. Accommodation of the two films in 
the camera gate is accomplished by replacing the usual mechanism 
by one adjusted to have a wider opening. The back plate of this 
mechanism is fitted with hard rubber plugs of varying heights, 
simulating the effect of a slightly curved aperture plate. The 
concluding section of the paper dealt with the correction of lenses 


necessitated by the introduction of panchromatic films. Lenses are 
now available which are corrected for red rays at a wave-length of 
6563 and for blue rays at a wave-length of 4340. 

At a second meeting held on February 5th at the headquarters of 
the Electric Association, Mr. J. E. Jenkins presented a paper entitled 
"Condenser Microphone Design." The paper dealt with the con- 
denser proper and the design of the amplifier. Curves were given 
showing the variation in audio response resulting from different 
damping conditions and dimensions of the diaphragm. The paper 
also dealt with the possible and actual effects of studio conditions on 
the pick-up of sound independently of the characteristics of the 

The Society regrets to announce the death of Arthur Gray, 
January 27, 1931. 

There is mailed to each newly elected member, upon his first 
payment of dues, a gold membership button which only members of 
the Society are entitled to wear. This button is shown twice actual 
diameter in the illustration. The letters are of gold on a white back- 
ground. Replacements of this button may be obtained from the 
General Office of the Society at a charge of $1.00. 


One of the chief reasons why our Society changed its form of 
publication from quarterly Transactions to a monthly JOURNAL was 
to permit the dissemination of information which is not made 
available at our conventions. The transactions of a society merely 
record the proceedings at the society's meetings whereas it is proper 
for a journal to publish any matter pertaining to the welfare of the 

Our Society will thrive only if each member takes a deep interest 
in its welfare. Having the interests of our Society at heart, each 
of you must have suggestions for making our JOURNAL and conven- 
tions of greater value to the industry. It is with this object in 
view, that at a meeting of the Board of Governors at New York City 
on December 19th, it was resolved: "That an open forum be estab- 
lished as a new department of the JOURNAL, in which might be pub- 
lished letters and communications from members relating to material 
in the JOURNAL or to other matters appertaining to the welfare of 
the Society, subject to the discretion of the Editor and Board of 

May I suggest correspondence on subjects such as the following: 

(a) Better ways of conducting the conventions. 

(b) Problems for research. 

(c) Problems for investigation by the various committees. 

(d) Discussion of technical papers appearing in the JOURNAL, 
with comments on the success or failure of their application. 

(e) Description of interesting or new developments which have 
come to your attention during your travels, thereby giving all the 
members the benefit of this knowledge. 

(/) Preliminary announcements of investigations and discoveries 
which are to be more fully reported at a later date in formal papers. 

Remember that the Society of Motion Picture Engineers is your 
Society and although many of us are widely separated geographically, 
let us meet monthly in the Open Forum. 

J. I. CRABTREE, President 




Agfa Ansco Corporation 

Audio-Cinema, Inc. 

Bausch & Lomb Optical Co. 

Bell Telephone Laboratories, Inc. 

Carrier Engineering Corp. 

Case Research Laboratory 

Consolidated Film Industries 

DuPont-Pathe Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theaters Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Paramount Publix Corp. 

RCA Photophone, Inc. 

Technicolor Motion Picture Corp. 


Prior to January, 1930, the Transactions of the Society were published quar- 
terly. A limited number of these Transactions are still available and will be 
sold at the prices listed below. Those who wish to avail themselves of the op- 
portunity of acquiring these back numbers should do so quickly, as the supply 
will soon be exhausted, especially of the earlier numbers. It will be impossible 
to secure them later on as they will not be reprinted. The cost of all the available 
Transactions totals $46.25. 



1917 { I 


1918 7 















































Beginning with the January, 1930, issue, the JOURNAL of the Society has been 
issued monthly, in two volumes per year, of six issues each. Back numbers of all 
issues are available at the price of $1.50 each, a complete yearly issue totalling 
$18.00. Orders for back numbers of Transactions and JOURNALS should be placed 
through the General Office of the Society, 33 West 42nd Street, New York, N.Y., 
and should be accompanied by check or money-order. 




Volume XVI APRIL, 1931 Number 4 



The Talking Film P. BONNEAU 399 

Sound and Speech in Silent Pictures.... ARTHUR EDWIN KROWS 427 

Effect of the Water Supply in Processing Motion Picture Film. 


The World's Most Powerful Microscope F. F. LUCAS 445 

Visual Aids in Teaching C. E. BAER 457 

Membership List 466 

Committee Activities 492 

Abstracts 495 

Patent Abstracts 503 

Book Reviews 511 

Officers 513 

Committees 514 

Committee Chairmen 517 

Contributors to This Issue 520 

Society Announcements 521 






Associate Editors 

C. E. K. MEES 


Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members $12.00 per year; to members $9.00 per year; single 
copies $1.50. Order from the Society of Motion Picture Engineers, Inc., 20th and 
Northampton Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 


Summary. The first part of the paper is mainly historical, tracing the develop- 
ment of the motion picture art, particularly from the French poim oj view. Various 
processes used for synchronizing sound and picture from about 1899 to the present 
are mentioned. Among these processes are those employing engravings on the film, 
and reliefs which act to vary the capacity in a high-frequency circuit. Reference is 
also made to magnetic wire processes and finally, the present-day method of recording 
sound photographically. Two variations of the latter process, viz., the fixed density 
method and the variable density method are explained. The discussion continues 
with various types of light valve recorders and sources of light. 

The second part of the paper deals with the particular processes now employed in 
France, discussing particularly the various mechanical, electrical, optical, and acous- 
tical processes which intervene between the studio and the review room. The matter 
of acoustics of the studio and the effect on the sound record is discussed at some length, 
as well as the effect of speed changes in the driving motor of the camera or recorder. 
Various other apparatus used in the studios are described. 

No technical man can afford to lack interest in, or to misunder- 
stand the essential principles involved in the sound pictures of today. 
In fact, one finds in them a marvelous linking of devices, and of 
electrical, mechanical, optical, chemical, and acoustic methods. 
The chief branches of physics have close analogies among themselves, 
and in the processes used in making sound pictures, these analogies 
are impressed on the electrician and the mechanic, as they are on the 
acoustic expert. Many problems present themselves to these tech- 
nicians between the moment when the microphone picks up the 
voice of the artist, surrounded by the scenery of the studio, and the 
time when the spectator, seated in a chair before the screen, listens 
to the reproduced sound; but these incidental problems are essen- 

* Annales desPostes Telegraphes et Telephones, XII (December, 1930), p. 1009. 
Translated by I. H. Parsons, Bell Telephone Laboratories, Inc. This article was 
abstracted primarily to give the French point of view on recording practices, and 
although some of the practices referred to are not in accordance with current 
American practice, the article contains many interesting features which should 
be placed on record. 

** Technical Director, Gaumont Studios, Paris, France. 


400 P. BONNEAU [J. S. M. P. E. 

tially analogous to, and always reduce themselves to, a study of the 
propagation of a sound wave over a telephone line. 

The discussion which follows is divided into three parts. The first 
part provides a summary of the history of sound pictures, from which 
the natural classification of the various processes in use follows. 

In the second part, the actual methods of operation and the most 
important apparatus utilized in the sound picture industry are 
examined. These will be considered in the order in which the 
operations occur; that is to say, beginning with the recording studio, 
the study terminates behind the screen of the review room, at the 
group of loud speakers used for reproduction. 

In the third part, the advantages and disadvantages of various 
systems are briefly discussed, suggesting the directions in which 
one should aim, and the goals toward which science and the ingenuity 
of research workers should be particularly directed. 


Phonographs. In the earliest days of sound pictures cylinder or 
disk phonographs were used almost exclusively, operated in syn- 
chronism with an ordinary motion picture film. Over thirty years 
ago numerous investigators conceived the idea of combining the 
phonograph and the cinematograph, but in practice two difficulties 
were encountered. In recording, the wax impression was not made 
electrically, but directly, by means of a stylus operated by the dia- 
phragm receiving the sound waves; it was therefore necessary for 
the artists to speak quite close to the receiver, which made it im- 
possible for them to move about. This was contrary to the technic 
of motion pictures, which requires, above all, the representation of 
motion. Moreover, in reproduction, it was necessary to place the 
phonograph behind the screen in order to produce the illusion that 
the voice came from the mouth of the subject in the picture; the 
phonograph had to be very powerful and had to be synchronized 
with the motion picture projector so that no divergence occurred 
in starting. 

Several tentative efforts were made in 1899 by Edison. To ob- 
tain a sufficient reinforcement of the sound in reproduction, three 
phonographs were used simultaneously; there was no synchronous 
coupling whatever between the phonographs and the projector and it 
was necessary for an operator to regulate the speed constantly in such 
a manner as to maintain synchronism of the sound and the picture. 

April, 1931] THE TALKING FILM 401 

The first actual industrial application was begun in France in 
1900 by the Gaumont organizations, which, under the leadership 
of their founder, M. Leon Gaumont, brought forth successively: 
in 1902, electrical synchronization of the phonograph and of the 
projector; in 1906, electrical recording on wax by means of a micro- 
phone and an electromagnetic recorder; a little later, the ampli- 
fication of sound reproduced on a phonograph by means of com- 
pressed air. 

Beginning in 1910, these different arrangements led to a system 
which was commercially exploited. The series of Gaumont 's "photo- 
scenes" and the reproducing apparatus termed the "chronophone" 
were distributed throughout France and abroad. Nearly four hun- 
dred of these appliances were placed in service before this expansion 
was stopped by the War; one of them was even used in New York 
for public demonstrations in June, 1913, at the 39th Street Theater. 

Finally, when thermionic amplifiers became practicable, the Gau- 
mont organizations brought out in 1918 (their patent is dated May 
15, 1918) the electrical reproduction of phonograph disks by means 
of an electromagnetic reproducer, which has since been known uni- 
versally as a ''pick-up." 

Sound Films. The recording of sound vibrations, not only on a 
phonograph disk but on motion picture film, followed from prin- 
ciples which had long been known. As a matter of fact many physi- 
cists have worked on the analysis of sound by the oscillograph, and 
on its synthesis, with purely scientific aims in view. Moreover, 
investigations undertaken since the middle of the last century for 
telegraphic picture transmission rendered the application of some very 
ingenious methods possible, which could immediately be applied to 
the recording of sound waves. 

Various Processes. We first find some old methods based on en- 
graving the edge of the film in such a way that this edge would be 
shaped into a curve reproducing the form of the sound vibrations. 
These indentations could be used either mechanically as in a phono- 
graph record, or optically to produce a telephonic current by passing 
before a selenium cell. This latter process was thought of in 1889 by 

Other similar but better perfected methods may be mentioned. 
These consisted in engraving a track to various depths in the film, 
after having softened it locally by means of a suitable solvent. 
There are numerous varieties of this process, among which may be 

402 P. BONNEAU [J. S. M. P. E. 

mentioned the Faucon- Johnson process and that which the German 
inventors, Bothe and Waltz, are attempting to develop. Waltz's 
method of reproduction is ingenious; it consists in passing the 
film with variable reliefs between two light metallic rollers. One 
is fixed, while the other is lightly supported on the film and more 
or less separated from the fixed roller by the thickness of the relief. 
These two rollers form a small condenser, of which the separation 
of the electrodes varies in reproduction according to the sound 
record. The two rollers may even be held at a constant separation, 
the variations of the dielectric being obtained simply by the varia- 
tions in the thickness of the celluloid film. In order to obtain 
sufficient sensitivity this condenser is inserted in a high-frequency 

In the category of films in relief, electrically resistant films should 
be included. Variations in the resistance of a track rendered more 
or less conductive are utilized in this case. This process, which was 
particularly recommended by Timm about 1911, does not seem to 
have been developed Lastly, a tendency to apply Poulsen's well- 
known magnetic wire process to sound pictures must be noted. This 
method was taken up and perfected by Stille. In this field, Ruhmer's 
attempts about 1909 should be mentioned; in these a metallic powder 
which could be magnetized was spread on the film. 

Photographic Recording Processes. Sound film processes which 
rely on recording sound photographically are much the most inter- 
esting, and the only ones which are practically used at the moment. 
These processes are divided into two very distinct categories: 

In the first category, the image of the sound vibrations forms a 
constant photographic density which, however, varies in width. 
This is termed the "fixed density method." The curve representing 
the sound vibration separates a uniformly dense photographic 
region from one which is uniformly transparent. This method of 
recording is carried out by displacing a very narrow luminous beam 
on the unexposed emulsion while the film is moved lengthwise at a 
uniform speed. 

The second category employs a track of constant width but of 
varying photographic density. This method is termed the "variable 
density" method. The successive density variations correspond 
to the variations of intensity of the sound. This type of recording 
is produced by varying either the brilliancy or the height of a fixed 
line of light which falls upon the film transversely while the latter 

April, 1931] 



passes lengthwise at a uniform speed. Fig. 1 indicates diagrammati- 
cally the way in which these two processes are carried out. 

The acoustic reproduction from the photographic sound record 
is brought about, in principle, by passing the brightly illuminated 
film at constant speed before either a real or a virtual slit. The 
light variations transmitted through the film to a photoelectric 
cell produce currents which are amplified to operate a group of 









FIG. 1. 

A diagrammatical illustration of the way in which the fixed density 
and variable density methods are carried out. 

loud speakers. This arrangement is utilized for both types of 
photographic sound record. It is for this reason that the different 
sound film processes of this category differ as regards the apparatus 
used for recording, but both types employ the same apparatus for 

The method most widely used for producing a fixed density record, 
that is to say, a record obtained by moving across the film a very 
narrow luminous image, consists in deflecting a ray of light by means 
of the mirror of a galvanometer. The English physicist, Duddell, 
took out a patent, dated November 10, 1902, which had this as its 



[J. S. M. P. E. 

object, and which can be considered as the prototype of the modern 
processes in fixed density work. Fig. 2 shows the two original dia- 
grams in this patent. The upper drawing represents the plan view 
of the recorder diagrammatically. We see at A the light source, 
at d a rectangular diaphragm, at m the small mirror of the oscillo- 
graph, at c a cylindrical lens which concentrates and narrows the 
beam of light to a very narrow line, by which the exposure is made 
at e on the film /, which unrolls from the magazine D toward the 

FIG. 2. The two original diagrams in Duddell's patent of 
Nov. 10, 1902. 

magazine D'. It is remarkable that, for this purpose, Duddell 
recommended the use of a Blondel bifilar type galvanometer and 
claimed priority for it in his patent. This galvanometer is almost 
universally used in practice for recording fixed density sound films. 
The lower diagram shows schematically the method of reproduction: 
the luminous beam issues from the source A, is narrowed at e, and, 
more or less diminished by the opaque record on the film, is received 
by the selenium cell s. One notices on these two figures, almost in 
contact with the film, a screen having a very narrow slit, the object 
of which is to limit the height of the light beam. The use of this 

April, 1931 ] THE TALKING FILM 405 

slit, which rapidly becomes filled with foreign matter, has had to be 
completely abandoned. It has been replaced by an optical arrange- 
ment by means of which the reduced image of an illuminated slit 
is formed on the film. This optical device has a larger slit which 
does not come in contact with dust in the path of the light rays. 

Indeed, the development of the method devised by Duddell has 
brought about some important improvements in the galvanometer. 
In fact, it has been possible to build bifilar instruments having a 
natural frequency of oscillation of over 10,000 cycles per second. 

There are other methods of recording with fixed density: The con- 
centrated light beam is passed through a small rectangular diaphragm 
whose length is controlled by the sound vibrations. This slit is 
generally formed by means of a horizontal slit in a diaphragm with two 
parallel wires very close together, forming a string galvanometer 
and arranged vertically (at 90 degrees) in contact with this dia- 
phragm. These wires, in receding from and approaching each other, 
cause the horizontal dimensions of the little aperture to vary. 

It is particularly in producing variable density photographic 
sound records that the ingenuity of investigators has been given 
full rein. The methods employed can be classified into two groups: 

(a) Those in which the intensity of the light source is variable 
and controlled by the intensity of the sound wave. 

(b) Those in which the pencil of rays from a constant light 
source passes through a valve whose characteristics vary as a function 
of the sound wave. 

In the first category, we find the devices of the Dutchman, Hedick, 
who in 1887, used the well-known properties of flames which can be 
affected by means of sound waves. About 1900, Ruhmer used an 
arc lamp for the same purpose and built a recording apparatus for 
sound waves which was termed the "Photographon." In 1903 Korn 
constructed an instrument having two electrodes between which elec- 
tric discharges were produced, by means of high voltages. Further- 
more, many experimenters employed simple incandescent lamps 
in which the filament possessed very little inertia. As a matter 
of fact, for this type of light recorder, tubes in which discharges are 
produced in a gaseous atmosphere are used almost exclusively. 
Such tubes are filled with argon, nitrogen, or helium under a pres- 
sure of a few millimeters of mercury. At a suitable voltage the 
space between the electrodes becomes luminous and forms a light 
whose intensity is related to the anode current by a law which is 



[J. S. M. P. E. 

almost exactly linear. There are many types of these lamps using 
luminous gas. One of the best is provided with a steel anode and 
an oxide-coated cathode of platinum. At 350 volts, the gas, which 
is rich in helium, emits an intense and highly actinic glow. 

In the same general class Goercke's tube should be mentioned: 
in this tube, near the two electrodes which are in a rarefied atmos- 
phere, a light is produced which varies as a function of the modulated 





FIG. 3. 

Piedfort's light valve recorder employing two 

intensity of a high-frequency current. This device has also been 
used for fixed density recording. 

In the second category, that is to say, in the group of recorders 
which employ a light valve, it is most important to mention the 
valve designed by the Bell Laboratories. It operates on the principle 
of the bifilar galvanometer, which we have already found used in the 
case of fixed density recording. But in this case, the valve is not 
required to cause variations in the length of the line of light trans- 
versely to the film, but rather in its width. These variations are 
ultimately impressed on the developed film as density variations. 

In this same category of light valve recorders fall the types with 

April, 1931] 



two gratings. These employ the principle patented May 4. 1894, 
by Piedfort for multiplex telegraphy over submarine cables. The 
optical arrangement used is shown in Fig. 3. By means of the 
galvanometer mirror, the image of the first series of slits is shifted. 
It will be seen that, depending on the superposing or divergence 
of the image of the first grating on grating No. 2, the light will pass 
from the maximum possible to complete extinction. 





FIG. 4. 

The light valve system employing Kerr's cell, 
using nitrobenzine. 


FIG. 5. The light transmission curve for the 
Kerr cell. 

The system derived from Kerr's principle, previously used for 
telegraphic picture transmission, must also be placed in the light 
valve class. This method has been extensively developed in Ger- 
many for sound film recording. The principle of the optical system, 
which is well known, is represented in Fig. 4. The recording system 
includes a light source of constant intensity, from which the light 
first passes through a polarizing Nicol, then through a Kerr cell using 
nitrobenzene, and finally through a second Nicol prism. The light 
transmission curve for the Kerr cell is shown in Fig. 5. Of course, 
only the nearly straight portion between A and B is used. The polar- 

408 P. BONNEAU [J. S. M. P. E. 

izing voltage for the cell is about 700 volts and the modulating voltage 
200 volts. 


We shall now examine the successive operations of taking pictures, 
recording sound, and reproducing it, the interconnection of which 
processes constitutes the sound film art. We use the term, sound 
film, intentionally; in order to restrict ourselves, we will set aside the 
branch of this industry which uses phonograph disks in synchronism 
with the pictures of a motion picture film. This branch, however, 
is important, and its applications to sound pictures are not as yet 
destined to disappear. Very appreciable progress has taken place 
in this direction, and it must be realized that sound reproducing 
appliances for disks alone are simpler and cheaper than those using 
photographic records on film. Certainly it can be admitted that 
soon the film process will render possible more perfect sound repro- 
duction than the disk method, for the photographic record has 
broader possibilities than the physical record obtained mechani- 
cally on a plastic substance. Looking at the question from the sole 
point of view of the sound quality, it may be said that at the moment 
these two methods are approximately equal. In fact, the reproduc- 
ing apparatus used in sound picture work is normally arranged for 
the use of either of these processes, and many distributors of sound 
films release the sound production in the film or disk form indiffer- 
ently. There is, however, a reason of a practical nature which will 
advance, for a long time to come, the cause of the disk. The sound 
track on the film rapidly becomes spoiled in use, while the part which 
carries the pictures remains in sufficiently good condition for a large 
number of further projections. If disks were employed from this 
point on, with the same synchronism and the same sound version, 
it would be possible to prolong the commercial life of the film. 

Fig. 6 shows schematically the different mechanical, electrical, 
optical, chemical, and acoustic processes which must be carried out 
between the studio and the review room. Fourteen may be counted, 
besides those at the beginning and end of the classification; the 
microphone diaphragm vibrates under the action of the sound waves ; 
this produces a feeble current which is amplified ; this current operates 
an instrument, which in the figure shown, is a bifilar galvanometer; 
the galvanometer modulates a beam of light; the latent image is 
formed on the film, reduced by development and the negative is 
obtained; the positive is printed from this, and then developed. 

April, 1931] 



By passing this positive before a photoelectric cell, a feeble current 
is formed, which, after amplification, operates the loud speakers. 
Such are the links in the chain which we are going to follow. It 
may be pointed out in passing that excellent experimental proof 
of the theories of vibratory phenomena is given by this chain. Also 
the degree of confidence which can be placed in certain perfected 
















15= SOUND 

FIG. 6. A schematic representation of the various mechanical, electrical, 
optical, chemical, and acoustical processes occurring between studio and re- 
view room. 

instruments is impressive, since this chain of fourteen distinct 
processes leads us, after the complete cycle, to a satisfactory result. 


The Studio. The sound studio is a large building into which no 
daylight or sound penetrates; in short, it is a place completely iso- 
lated from the outer world. The walls of the studio must meet two 
conditions: they must prevent the passage of external noise, and 
they must, inside, partially absorb the sound waves which fall on 
them in order to avoid excessive reverberation. It is impossible in 

410 P. BONNEAU [J. S. M. P. E. 

practice to realize these two conditions by means of one single 
homogeneous material. In fact, a substance prevents transmission 
of the sound wave when it reflects it completely, and if it is capable 
of thus totally reflecting the sound, it is because none is absorbed. 
In spite of this fact, some firmly established legends exist on the 
subject, and one finds in commerce materials, with magic properties, 
of which one layer would suffice to form ideal walls. In general, 
materials' of a fibrous or porous texture provide, if used alone, a 
very inferior acoustic insulating capacity compared to that given 
by heavy, hard, and impermeable materials. In fact, to build a 
wall which prevents the passage of exterior noises, one of two equally 
efficient methods are used: either a thick wall of heavy materials 
may be built, or a series of materials in which the speed of sound 
has very different values may be used. Following this second 
method, structures with two walls are built, having two partitions 
separated by an air space. For a moderate weight this offers a 
high degree of acoustic insulation. Furthermore, in order not to 
lose the benefit of an expensive type of construction, the partitions 
must not be connected together by sound-conducting material, 
and the doors and windows must be sound-proof as well as the 
walls themselves. This is why the doors are usually very thick, 
of two layers, and with perfectly fitting seams. A wooden stage is 
necessary for supporting the scenery; attempts are made to isolate 
it from the floor by resting it on a layer of massive insulating material. 
Finally, to prevent the strong vibrations on the stage from being 
transmitted to the building, its foundations are surrounded by a 
continuous depression. 

Inside the studio a microphone arranged to receive an artist's 
voice will pick up three sound effects in succession: first, the energy 
which comes directly from the mouth of the performer; then, the 
sound waves which are completely reflected as echoes by the large 
plane surfaces of the walls and scenery; finally, a continuation 
of the sound, which persists for an appreciable time, and which 
is due to a multiplicity of secondary reflections following each other 
until the initial energy has been practically absorbed. This last 
phenomenon constitutes the "reverberation" of the sound, which is 
measured by the time necessary for the sound intensity to fall to 
one-millionth of its initial value. This phenomenon is also some- 
times called the "room effect." 

The study of reverberation forms the most important part of 

April, 1931] THE TALKING FILM 411 

architectural acoustics, a science which has naturally been con- 
siderably developed since the arrival of sound films. In its details, 
the study of reverberation is very complicated, since it depends on 
the wave-length of the sound, on its intensity, on the complexity of 
its harmonics, on the size of the room, on the structure and nature 
of the walls and all the obstacles reached by the sound waves. For- 
tunately, as a basis for this subject, there is a simple formula, due 
to Sabine, according to which the reverberation is proportional to 
the volume of the room and inversely proportional to the sum of the 
absorbing units formed by the walls and other obstacles. It is for 
this reason that in a cathedral where the walls have a negligible 
absorbing capacity, the reverberation time is often over ten seconds, 
while it is practically zero in a padded telephone booth. 

In a sound picture studio the formation of definite echoes is 
obviously undesirable, but the walls are not generally sufficiently 
distant for the effect to be marked. This is not the case with 
reverberation phenomena which are, on the contrary, very im- 

Should reverberation in a studio be considered favorable or in- 
jurious in taking sound pictures? It is a question of degree, which 
the director should take advantage of, if possible. In a studio which 
is too dead, giving too short a reverberation time, the sounds appear 
suffocated and do not carry ; the effect of distance is absent and music 
lacks volume. In a live studio which is too large, with a reverbera- 
tion time of several seconds, the sound is reflected, giving the effect 
which is familiar in a cathedral; music takes on relief, the various 
tones being more easily differentiated. The spoken word becomes 
confused, for on each spoken syllable are superposed reverberations 
of preceding syllables. Recording carried out under such conditions 
will appear greatly distorted, for it must not be forgotten that in 
this case it is a microphone which picks up the sound waves, and not 
the two ears which possess a physiological capacity for distinguishing 
one sound among a medley of others. This is why before taking 
sound pictures, the reverberation time of the studio must always be 
tested by listening with only one ear. 

In the earliest sound pictures, studios were deadened excessively 
by furnishing them with hangings. Then it was noticed that much 
more life was given to sound reproductions by introducing a reason- 
able degree of reverberation, varying for example, from 1 to 2 seconds. 
It then became sufficient to line the studio walls by means of panels 

412 P. BONNEAU [J. S. M. P. E. 

of compressed vegetable materials, of which a considerable variety 
exists. These materials possess an excellent absorbing power, which 
reaches 50 per cent of the energy received as sound, a value com- 
parable to that of a padding formed of long hair of good quality. 
Most modern studios employ an exterior wall separated by an air 
space from an interior wall of compressed material. 

The materials used for insulating the walls acoustically are, in 
general, easily inflammable and must be carefully fireproof ed. Fire 
risks are very great in the studio, where the overheated atmosphere 
dries such materials very rapidly. That is why attempts are made 
to replace them by drapings formed from asbestos wadding, from 
glass wool, etc. 

There is a very practical method of reducing the reverberation 
time by dealing with the shapes of the reflecting surfaces rather 
than with the material used. By corrugating the walls asymmetri- 
cally, the dispersion of sound waves is favored and their energy is 
rapidly attenuated. A hemp mat, even if somewhat stiff, hung with 
large folds, provides an absorbing power of 75 per cent. By covering 
the walls and stage more or less in this way it is possible to vary the 
reverberation time according to the effect desired. This method has 
been used in the auditorium of the Gaumont Company, so that the 
absorption of the walls may be quickly regulated as wished. It 
should be remarked that this absorption is selective, since, depending 
on whether the folds of the cloth curtains are wide or narrow, the 
absorption of low or high notes is favored. 

A clever director can produce unexpected effects from the sound 
reverberations. The use of this phenomenon gives him a means of 
creating a more or less accentuated sensation which may be called 
" sound perspective," and of producing physiologically a kind of 
depth to the projection screen. 

It is often desired to combine several different sounds on a single 
film, for example, a dialog and a distant musical accompaniment. 
If the two types of sound have been recorded with very different 
reverberation times, they can be combined without danger of being 
confused by the ear when reproduced, since the ear knows intuitively 
that the two sources of sound have distinctly different points of origin. 
Such measures are, however, very difficult, for it would be necessary 
to give an exact impression of the reverberation time corresponding 
to the volume of space represented on the projection screen. Theo- 
retically, it would even be necessary to consider in recording, the 

April ,1931] THE TALKING FILM 413 

reverberation time of the motion picture theater to be used for pro- 
jection, and to know how its characteristics vary depending on 
whether loud speakers with horns or baffles are employed. 

All this is further complicated by acoustic disturbances contributed 
by the shapes of the scenery. There are always some points at 
which the sound becomes concentrated and at which are created 
interferences and resonance effects which our two ears reject physio- 
logically in ordinary life, but which the microphone, a single ear, 
picks up indiscriminately. Furthermore, the different parts of the 
scenery do not all offer the same degree of sound absorption, and 
this absorption differs for low and high notes; sometimes it is only 
necessary for an artist to move a few feet on a set to suddenly change 
the pitch of his voice when heard through the agency of a micro- 
phone. Naturally this phenomenon always causes surprise; on 
first thought one attributes it to a fault in the microphone or to a 
speed variation in the recording apparatus. These annoying effects 
are diminished by using light materials of coarse texture with 
sufficient absorbing capacity. Thin panels of compressed vegetable 
materials, very porous and painted with sizing, are very useful in 
this case. 

Studio Fixtures. The motion pictures are taken on a first film, 
by means of the motion picture camera. Sound, picked up by the 
microphone, is recorded separately at the same time, but on a second 
film and by another apparatus termed a sound recorder. From 
these two negative films, of which the first is the picture and the 
second the sound film, a single positive film will finally be 

The only apparatus which we should find in the studio is, in theory, 
the camera and the microphone. The sound recorder is usually 
placed in a special room, which is often some distance from the 

The sound recorder and the camera are driven by synchronous 
electric motors, thanks to which, one is certain that the two machines 
will use exactly the same amount of film in a given time. 

The motors generally used are those whose speed is in synchronism 
with the frequency of the alternating current supply. Within what 
limits can this method provide a sufficiently constant speed, so that 
an expert ear will be unable to notice any tone variation during re- 
production? The smallest musical interval, which the human ear 
can detect, establishes what is termed the sensation of coma. This 

414 P. BONNEAU [J. S. M. P. E. 

interval is approximately 5 savarts.* It may easily be calculated 
that to produce an equivalent interval in the speed of a synchronous 
motor, it would be necessary to change the frequency of the current 
from 50 to 50.6 cycles per second. Such a large variation is very rare 
and, without an accident, could only take place gradually, in a period 
greater than a minute, because of the enormous inertia of the rotors 
of the alternators. But the sensation of coma corresponds to a 
sudden variation. In the case of a slow variation the ear can only 
notice a greater interval. Admitting that most supply companies, 
because of the necessity for interconnecting central stations, find 
it necessary to maintain an exact frequency for their current, it 
will be seen that the use of synchronous motors for operating sound 
film apparatus assures a sufficiently constant movement of the 

In spite of the delicacy of the camera mechanism, a certain amount 
of noise is always caused by it which must be prevented from reaching 
the microphone. This is why this apparatus, its motor, its support, 
and even the cameraman, are frequently enclosed in a sound-proof 
booth, which can be rapidly moved about the stage. In practice it 
is preferable to enclose the appliance and its motor in a sound-proof 
box. Alternatively, this box being of necessity very cumbersome, 
the camera and motor may each be placed in a padded container, 
connection being made by a noiseless flexible coupling. 

The importance of keeping out extraneous noises from the studio 
while pictures are being taken has imposed special precautions in 
lighting the scenes. To "shoot" a film a considerable amount of 
light energy must be used, amounting to several hundred kilowatts, 
which are used in a large number of lamps and arc light projectors. 
If we recall the properties of the singing arc, it will be realized that 
the ordinary type of arc lamp produces a whistling whose note 
corresponds to the variations, however small, of the continuous 
current feeding them. The studio arcs follow this rule and sing 
very faithfully on the note of the commutator at the substation. 

One must, therefore, prohibit arc lamps in the studio for sound 
picture work, and use incandescent lamps. We have gone a long 

* Translator's Note. The "savart" is apparently equal to the musical term, 
the "cent." The cent has the common ratio 1: \/2 = 1:1.0006 approximately. 
From this difference of 6 parts in 10,000, 5 cents (or 5 savarts) would equal 30 
parts in 10,000 or 0.3 per cent, the accepted value for frequencies between 500 
and 4000 cycles per second. 

April, 1931] 



FIG. 7. A faceted projector using a 10 kilowatt lamp 
for providing a fairly diffuse beam of light. 

way in this direction since 10 kilowatt lamps have been built for this 
service. Fig. 7 represents a faceted projector which gives a fairly 
diffuse beam of light. Fig. 8 shows a large mirror l x /2 meters in 
diameter, combined with a 10 kilowatt incandescent lamp. 

These different lighting systems are inconvenient in that they 
radiate an enormous amount of heat energy. Studios thus equipped 
must be supplied with good ventilation, so that the overheated air 



[J. S. M. P. E. 

can be rapidly replaced between the filming of two scenes. Also, 
it is difficult, by means of an incandescent lamp, even if backed by 
a mirror, to obtain an intense, uniform, and well directed light 

FIG. 8. A large mirror projector I 1 /* meters in diame- 
ter, using a 10 kilowatt incandescent lamp. 

beam, giving, for example, the impression of a ray of sunlight which 
will produce some shadows and sharp outlines. 

To obtain certain lighting effects in the case of large scenes, it has 
been necessary to return rather definitely to arc lamp projectors. 
To diminish the noise, a strong reactance coil is arranged in series 
with each arc. This remedy is often insufficient, and the commutator 

April, 1931] THE TALKING FILM 417 

harmonics must then be filtered out completely by connecting across 
the generator a battery of electrolytic condensers of a thousand 
microfarads capacity or greater. It is not sufficient to prevent modu- 
lation of the flame from the crater by variations in the supply current 
to make an arc absolutely silent. The burning of the carbons natur- 
ally produces humming and crackling noises which are difficult to 
eliminate. To diminish these noises, it is necessary to deal with the 
volume, the shape and the course of the flame by means of a suit- 
able electromagnetic blower and to design the metal covering of the 
projector so as to prevent the formation of a resonant chamber. 
Some successful tests have recently been carried out for the studios 
with a diffuse, cold light which is nearly white, using a combination 
of mercury vapor and neon lamps. Finally there may be mentioned, 
for the same purpose, perfected tubes filled with argon under a 
pressure of 5 millimeters and fitted with cadmium cathodes. Such 
tubes give a very intense white light when operated at 25 amperes. 

The Microphone. One of the principal factors on which the quality 
of a sound film depends is undoubtedly the microphone. It is 
desirable that it should have as uniform a sensitivity as possible from 
30 to 30,000 cycles per second, that it should be stable, that it should 
not produce appreciable crackling or blasting noise, and that it should 
not be too highly directive. The condenser microphone and Reisz's 
microphone are principally used: the latter employs a very thin fixed 
layer of powdered carbon. Each type has its partisans; but it must 
be admitted that the judicious use of either leads to substantially 
identical results. The condenser microphone must be near the first 
amplifier tube, so this is generally mounted in the base of the micro- 
phone support. This results in a rather cumbersome arrangement. 
The Reisz microphone, which generally requires one less stage of 
amplification, can be conveniently connected to the amplifier by a 
long line and is sufficiently compact to be hidden in the drapings of 
the set if necessary. Lastly the sensitivity of the Reisz microphone 
decreases less rapidly than that of the condenser type when the 
source of sound is moved farther away. 

Generally the microphone is hung in front of the artists by means 
of a boom, the height of which is adjustable. In principle, it is 
better to reduce the sensitivity of the microphone and to use several 
of them, three, for example, conveniently located on the set. If 
music is being recorded, one can, in this way, regulate the relative 
importance of the different parts of the orchestra in monitoring. 

418 P. BONNEAU [J. S. M. P. E. 

Also, in recording voices, the artists can move about freely without 
variations of distance causing too much variation in the audition. 
Most important of all, by requiring a lower degree of sensitivity in 
each microphone, a smaller proportion of foreign noises and reflected 
sounds is recorded. The placing of the microphones obviously 
depends on the roles of the artists and on the field covered by the 
camera, that is to say, on the scenario. Locations can only be 
chosen with a complete understanding of the acoustic conditions 
of the studio and its scenery. 

We must, on this same subject, note the efforts made to use micro- 
phones in combination with large concave surfaces which act as 
collectors of sound waves, in order to obtain special effects or to more 
completely exclude parasitic noises from the sound it is desired to 

The Control of Sound. The different microphones working in 
the studio can be controlled together by means of special mixing 
circuits, or alternatively, connected in sequence. Besides this, 
it is necessary every instant, to decrease or increase to a suitable 
degree, the magnitude of the microphone current, not only to ob- 
tain a natural mixing or a special effect in sounds recorded, but also 
to maintain this amplitude within the limits imposed by the process. 
Lastly it is necessary to control by ear the quality of the sound im- 
pressions picked up in the studio, throughout the recording process, 
thus checking the correct performance of the microphone and the 
recording amplifier. 

These three functions, judicious placement of the microphones, 
regulation of the intensity, and control of quality, are carried out by 
a monitor, who is usually located in a room adjoining the studio. 
This room has sound-proofed walls and communicates with the 
studio by a window which enables the monitor to watch the per- 
formance of the artists. This window, which must also prevent 
the passage of sound, is formed by a series of several thick glasses, 
separated by air spaces. The monitor has before him a panel which 
carries the controls of the different microphones and the graduated 
volume indicators for each microphone. These circuits are naturally 
designed so as not to produce frequency distortion in transmission. 

A loud speaker is located in the same room and repeats every- 
thing picked up by the microphone in the studio to the monitor, 
thus enabling the quality of the sound to be controlled. Theoreti- 
cally, for this control to be complete the acoustic output of this 

April, 1931] THE TALKING FILM 419 

speaker should be identical to that given by the loud speaker to be 
heard later by the audience in the theater. Therefore, between 
the studio microphone and this control speaker the entire series of 
operations necessary in making and reproducing talking film should 
be interposed. This condition is approached by using a control 
speaker and amplifier identical to those used in the motion picture 
theaters, and by tapping off the microphone current in the circuit 
of the recording machine after it has passed through as many trans- 
formations as possible. A further step in this direction is taken by 
monitoring, in addition, the light modulation of the recording unit 
by using a photoelectric cell of the type employed in the reproducing 
machines. For this purpose, it is sufficient to locate this cell further 
along the light beam producing the photographic exposure. The 
cell is excited through the unexposed film, which passes about 5 per 
cent of the incident light. Alternatively, the cell may be placed 
at the side of the light beam, part of the latter being deflected into it 
by means of a prism. In short, by this arrangement, the chain 
of operations is duplicated, with the exception, of course, of the print- 
ing process and of the chemical process of development. 

The bay window which communicates with the studio does not 
always afford a view of the scene when the latter is entirely sur- 
rounded by hangings. For this reason, in certain cases, it is pre- 
ferable to install the monitor and his appliances in a movable booth 
which is enclosed by sound-proof glass. This booth, which contains 
a means of transmitting instructions and from which the sound can 
be controlled, is rolled into the studio close to the scenery, so that 
the monitor will lose none of the action which takes place. In this 
manner, the director can, if he wishes, take his place in this booth 
and assure himself of the quality of the sound effects. 

Let us watch the monitor at work. Posted behind the glass 
windows, he sees the artists, and when they speak, hears them 
indirectly through the medium of the control loud speaker. He 
has, therefore, the illusion of being near them, although actually 
separated by many thicknesses of glass which insure silence. The 
scene is repeated. He listens, and communicates his impressions 
by microphone and loud speaker to the director. He points out any 
cracking noises or unpleasant intonations, increases or decreases 
the sound intensity, modifies the orientation of the microphones, 
and indicates any acoustic anomalies produced. His control, which 
is exercised through the medium of a microphone, is much more 



[J. S. M. P. E. 

critical and severe than that of the director in the studio; and yet 
in the last analysis both ultimately rely on the judgment of their 
ears, which are accustomed to the same tolerances. As regards the 
monitor, this is a very curious case of physiological lack of adapta- 
tion which simply proves that our reproduction by microphone and 

FIG. 9. Recording amplifier used 
in the Gaumont Studio. 

FIG. 10. Interior of the record- 
ing amplifier shown in Fig. 9. 

loud speaker, while it appears satisfactory, should not be confused 
with a natural process. Having determined the sounds to be recorded 
by several repetitions controlled in this manner, the scene is at last 
definitely shot. During this process the monitor restricts himself to 
adjusting the attenuators in the microphone circuits in order to 
perfect the regulation. In this he bears in mind, not only the 

April, 1931] THE TALKING FILM 421 

general impression desired, but equally the size of the figure which 
will appear on the screen as well. It is evident that a performer in 
the front will speak more loudly than one toward the rear of the 

There is an indirect method of control used in some studios, which 
consists in recording on wax with an electromagnetic phonograph 
recorder at the same time that the photographic recording is made. 
A few seconds after recording the wax record can repeat the sound 
just recorded by using a pick-up and operating a loud speaker in the 
studio. This arrangement is useful in that it enables the performers 
to correct themselves; but it is obviously less efficient, as regards the 
final result, than control effected during recording by means of a 
photoelectric cell placed in the recorder behind the unexposed film. 

The Amplifier. According to the arrangement of the rooms, the 
recording amplifier is located either near the monitor or in a special 
room, generally the recording room. 

It is usually a three- or four-stage amplifier, coupled by resistances 
and capacities, and built with very great care. Its response to differ- 
ent frequencies should obviously be related to the responses of the 
microphone and the sound recorder employed, which latter it is diffi- 
cult to modify. The amplifier is therefore equipped with equalizing 
circuits which the technical staff frequently check, and on which 
the quality of the talking film depends to a large degree. 

Fig. 9 shows a recording amplifier. The measuring instrument 
located at the top of the panel is a dead-beat milliameter with a very 
large scale, which is connected to the output of the detector circuit 
and indicates the average value of the sound picked up by the micro- 
phone. Fig. 10 shows the interior connections of this same am- 

The recording amplifier and all circuits directly or indirectly 
connected to the microphones must be suitably protected against 
external inductive and electrostatic effects. This precaution is par- 
ticularly necessary when the studio is subject to electromagnetic 
fields produced by high-voltage supply cables for lighting purposes. 

The Recording Machine. The sound recording machine includes: 
a mechanical device driven by a synchronous motor and designed to 
drive the film at a very constant speed ; film magazines ; a lamp and 
a special optical arrangement which generally includes some per- 
fectly corrected cylindrical lenses; the sensitive recording agent, 
which may be a light valve, Kerr cell, or bifilar galvanometer; and 



[J. S. M. P. E. 

finally an optical arrangement enabling the operator to control 
the recorded light variations continuously, either by means of a micro- 
scope, or by a device which projects the magnified spot of light. 

In one type of recorder the light falls on the film on the circum- 
ference of a toothed drum, which carries it along without any vibra- 
tion or slipping. Such a regular movement demands special pre- 
cautions. These consist in connecting the drum to the driving shaft 

FIG. 11. A Gaumont recorder of the Peterson- Poulsen type. 

of the motor through a "mechanical filter." It acts, on the rigid 
series of shafts and gears, to oppose propagation of vibrations of dif- 
ferent frequencies, of which the lowest is obviously equal to the fre- 
quency of rotation of the synchronous motor. Very perfect mechani- 
cal filters can be made in which the required damping is introduced 
by means of liquids. The film perforations are not always perfectly 
regular. The distance between two successive perforations, termed 
the "pitch of the film" is not always precisely 4.75 mm., its theoretical 
value. It follows that some disturbances in the passage of the film 
may be introduced by the toothed drum which carries it forward. 
This is why, in a second type of recorder, it is preferable to move the 

April, 1931] 



film by means of a smooth roller} to which it is caused to adhere by 
means of pressure pads. This smooth roller is keyed to the shaft of a 
larger flywheel which provides steady movement. 

Fig. 11 shows a Gaumont recorder of the Peterson-Poulsen type. 
In this machine, the film is the driving agent and turns the flywheel 

FIG. 12. Special recorder developed for maintaining constant 
tension on the film band and to counteract other defects usual in 

which is quite free and is employed merely because of its inertia. 
In some other machines, on the contrary, the smooth cylinder carries 
the film forward. But here some difficulty is encountered. The 
standard conditions for synchronizing sound film require that a length 
of film equivalent to 24 frames pass every second, or what amounts 
to the same thing, a length including 96 perforations. But these 96 
perforations represent an indefinite length, for the pitch of the film 



(J. S. M. P. E. 

is never exact and it can, moreover, contract a certain amount in a 
short time. If, therefore, the film be moved by a smooth flywheel the 
speed of rotation must be regulated to maintain the passage of 96 
perforations per second. Some very ingenious arrangements have 
been built which achieve this result automatically. 

FIG. 13. The regulating mechanism on the rear side of the 
recorder shown in Fig. 12. 

Unsteady film movements during recording cause flutter of the 
voice in reproduction, or an intolerable tremolo or vibrato. Vibra- 
tions in the film during recording of large amplitude introduce a 
less disagreeable sensation when reproduced; but in the voice a 
certain thickness of pronunciation is noticed, and in musical notes 
a rather unpleasant effect. Lastly, very rapid longitudinal vibra- 
tions in the film, and those of extremely small amplitude, are not 

April, 1931] 



directly audible in reproduction, but can cause, when very high notes 
are recorded, a flutter which diminishes the purity of the reproduced 
sound. Unexposed film is, unfortunately, a material which does not 
lend itself well to such severe requirements. It is elastic to a marked 
degree and vibrates when stretched. It rapidly contaminates things 
against which it is pressed. Moreover, film manufacturers are com- 
pelled to cover it with a viscous coating, which introduces unequal 
degrees of friction during unwinding. The object of this coating is 

FIG. 14. An automobile installation for taking sound pictures out-of-doors. 

to prevent the formation of electrostatic charges which expose the 

Recorders are made in which the film movement is protected 
against these difficulties. Fig. 12 shows the mechanical part of such a 
machine. The means adopted enable the tension of the film band 
to be regulated throughout its course to one constant value, which, 
may be as small as desired. Fig. 13 shows the regulating mechanism 
on the other side of this recorder. 

The optical system of the recorder must be very accurate. The 
light beam which exposes the film must be very fine and sharp, with 
a height of about 0.025 mm., without stray light, degraded zones or 


chromatic residues. It must also possess a very great luminous in- 

The bifilar galvanometers used in sound film recorders are very 
highly perfected instruments. Their natural oscillation frequency 
sometimes exceeds 10,000 cycles per second. The mirror is generally 
very small, its sides not exceeding 0.3 or 0.4 mm. The choice of the 
liquid used for damping is of great importance, for on its viscosity 
depends the critical damping of the equipment. 

Mobile Installations. We have reviewed the studio and its lighting 
arrangements, the camera for taking pictures, the microphone, the 
monitor's controlling instruments, the amplifier, and the recorder. 
Instead of locating these appliances in definite places, it is possible 
to install the control apparatus, the amplifier, and the recorder in 
booths mounted on wheels which are brought on the stage before 
the scenery. We are led to this arrangement less from technical 
considerations, than from the flexibility thereby introduced in working 
conditions, and because it provides a better means of supervising 
the personnel responsible for the sound quality. This method is 
only adapted to simple cases, however, but without doubt, simplicity 
is one of the characteristics toward which recording apparatus will 
tend more and more in proportion to its improvement. Finally it 
must be pointed out that similar installations are built into automobile 
trucks for taking sound pictures out of doors. See Fig. 14. 


Summary. According to this writer the new factor in the talkies is sound for its 
own sake and not speech, speech having found its place long ago in the printed captions 
of silent films. Study of these old subtitles, it is said, quickly defines screen dialog, 
while pure sound, no longer confused with spoken words, becomes a great artistic 
force. It was explained when presented, that this paper was really a chapter in 
"The Talkies," an immediately forthcoming book. Its appearance here is with the 
express permission of the author and of the publishers, Henry Holt & Company, of 
New York. 

The voice that is now brought to the heretofore silent screen is not 
in itself a new expression, but a new aid to expression. That it 
enables the artist to approximate life more nearly is comparatively 
unimportant, because the purpose of art is not the precise imitation 
of life but its interpretation. The films of the future will not be 
any more original in essential thought because of the super-addition 
of voice than bygone silent pictures; but because of voice their 
expression will be more flexible. 

The prime caution is never to think of the spoken word merely 
as sound. The voice makes a sound, but the word uttered may ex- 
press the reverse of sound. For instance, the clerk of the court may 
call out in stentorian tones, ''Silence." Or, going into other seem- 
ing contradictions, the well-known giant, muttering his "fe-fo-fi- 
fum," may continue, "I smell the blood of an Englishman." Or 
Gaffer Hexam (in Our Mutual Friend) may remark, as he steals a 
sixpence from a body floating on the Thames, that, "It feels cold 
and clammy and wet." Or the proud Balboa, extending his vision 
by poetic license from "a peak in Darien" to the Pacific Ocean, may 
utter raptures concerning what he sees. In short, the spoken word 
may easily appeal also to any of the five senses other than that of 

So it is that the spoken word is usually, and perhaps quite in- 
variably, a symbol for something else. It requires translation by the 
* A chapter from The Talkies, Henry Holt & Co., New York, N. Y. 
** Electrical Research Products, Inc., New York, N. Y. 



listener, whose imagination completes the suggested idea. It is 
that something else whatever it may be that measures the true 
effectiveness of the speech. Speech is the vehicle and not the end. 
The eloquence of Demosthenes, as that of Lincoln, was less in what 
he said than in what he literally thought. Thus it is that the expert 
stage dramatist writes his play not in words but in the ideas that 
the words are intended to convey the reactions of the audience; 
and in this attitude of mind he is able to detach himself from the 
tyranny of words as such, and not use them at all if some of the other 
resources of his medium will at the given moment serve him better. 
In the theater of today dialog is crisp and snappy in its interchange 
partly because the great alteration in living conditions demands a 
more telegraphic style, and more because many other factors have 
been developed to carry on the play. Shakespeare's stage was so 
meagerly equipped that the dialog had to state that the scene was 
a forest, a palace, a street that it was day or night, and many more 
clues to circumstance that a random dip into any of his master- 
pieces will soon disclose. Nowadays scenery and lighting particu- 
larly relieve dialog of these unfair burdens and relate it far more 
nearly to e very-day speech. 


Strictly speaking, the strange new element is sound and not speech. 
Speech has been joined with motion pictures since their infancy in 
the shape of the printed "titles" or "legends" or "captions" 
upon the screen; and in the artistic sense speech of that sort is 
not much more second-hand than that which is directly spoken. 
As the word that is heard by the ear commonly has to be translated 
afterward by the brain as something other than sound, the printed 
word seen by the eye frequently also has to be translated because 
it has nothing to do with sight directly. 

When the talkies permanently came, speech was already so far a 
part of motion picture practice that one-third of the footage of the 
average reel consisted of titles. Attempts had been made, every 
couple of years, to prove that the motion picture art was in its zenith 
when a picture had no titles, among the interesting later produc- 
tions of this sort being a version of James Whitcomb Riley's The 
Old Swimmin' Hole, starring Charles Ray, and The Last Laugh, 
starring Emil Jannings and directed by another superb artist, 
F. W. Murnau. But because speech, even in printed title form 


is so naturally and easily a part of motion picture appeal, its elimina- 
tion upon such arbitrary grounds as provided by what here seems 
to be an over-nice and possibly mistaken artistic sense, has not been 
approved by the industry at large. On the contrary, titles have 
been pushed to the apparent limit of their expression, the records 
showing a wide variety of experiments to develop their effectiveness. 


As many years ago as the heyday of the old Lubin Studio at Phila- 
delphia, there was tried out a scheme whereby the witnesses in a 
courtroom scene gave their testimony in words double-exposed in 
dark areas over their heads on the actual picture. In a much later 
but now long-past feature called, if memory serves true, Sporting 
Life, the action of the scene suddenly ' 'froze," so to speak, and be- 
came a background of the printed title imposed over it a method 
tried anew by George Loane Tucker in 19151916, when that gifted 
producer was director-general of the then recently organized Goldwyn 
Pictures Corporation. 

The cut-and-try worker, urged to explain the abandonment of 
these devices, probably will say after brief reflection that mechanical 
delays entailed, and, above all, the item of translation for the foreign 
market, made them impractical. The fact lies deeper. They were 
given up because in effect they didn't seem right the titles didn't 
"get over" as well as by the established plan of "cutting" them 
in. And whether those persons in the game divined the reason or 
not, it was this: the spectator appreciates best when he is able to 
concentrate; and his mind is so constituted that he concentrates 
best on one thing at a time. To watch the scene in the courtroom, 
however familiar it already may have become, to restudy the orienta- 
tion of characters and their varying facial expressions and at the 
same time attend their speech presented in this fashion, was a little 
like dividing one's attention over a three-ring circus. 

Now, of course, in the regular theater one does not literally blot 
out the scene while he listens to the speech and yet, if the produc- 
tion is carefully made, that is, in effect, what happens. As in con- 
centrating on a word one is reading on a printed page he is also vaguely 
conscious of an area of printed text around the focal point, the en- 
grossed audience listens to the player's telling words with a momen- 
tary dimming of the unrelated parts of the scene, the dimming being 
done by themselves. If attention is genuinely concentrated on the 


speech, the physical scene, to all intents and purposes, is not there 
save as one wishes to recall it. And what the venerable "cut-in" 
title does is artificially to assist such concentration by complete elimi- 
nation of the scene for a brief interval. Thus, the universally used, 
traditional title was, in one respect at least, firmly rooted in approved 

The stumbling-block here was the lack of uniformity in the audience 
itself. One person could read and appreciate quicker than another; 
and if he was not loud in his complaints that the title was held on 
the screen too long in other words, that the scene was blotted out 
too long the tenuous thread of interest snapped for him and he 
became restless. In this quandary the producers hit upon a device 
which was to decorate the title background with something that 
would divert the eye that too quickly had exhausted the meaning 
of the lettering. Being specific about it, probably the first deco- 
rated titles were made about 1908 by Richard Klaussen, the artist 
for many years in charge of the title department for the old Vita- 
graph Company of America at Brooklyn, N. Y. They seem to have 
been re-invented independently a few years later at the Thomas H. 
Ince Studios in California, by Irvin V. Willat and Mon W. Randall, 
the former then a master-cameraman and the other an artist less 
celebrated then than later for a highly original, vigorous technic. 
The Vitagraph Company had virtually abandoned the decorated 
title because there were too many other novelties to engage public 
attention for films; but early in 1915 the Ince picture Peggy, starring 
Billie Burke and with decorated titles throughout, was submitted 
to the distributors, Triangle Film Corporation, with a request for 
approval of the title backgrounds, in particular, that the practice 
might be continued for all Triangle-Ince releases. Approval readily 
given, the adornment became regular practice not only for the Ince 
division but for most of Triangle's competitors. Curiously enough 
it never was favored by D. W. Griffith, who at that time headed an- 
other division of Triangle. But the public liked it; and an even 
more potent reason for widespread adoption was the fact that it 
helped so much to "pretty" or "doll up" otherwise mediocre films. 

In the half-dozen years following those hi which workers in the 
first celebrated companies accepted and developed such basic ad- 
vantages as the close-up, fade-back, double exposure, one-to-one 
shooting and shooting through scenes painted on glass, there was no 
organization that contributed more to picture technic than that at 



Culver City, California, dominated by the far-seeing genius of Thomas 
H. Ince. Hence the eager interest in title development of his chief 
of camera staff, Irvin Willat, was aided and abetted. Willat car- 
ried title decoration to its high-water mark represented by such 
achievements as one in a play of big city politics, starring William 
H. Thompson and Charles Ray, showing a living spider actually 
ensnaring a fly, and, more remarkably still, a tiny frieze with living 
figures acting out an allegorical prologue back of the opening titles 
of A Gamble in Souls, starring William Desmond. 


These experiments were only incidental to other pioneer work 
which had to do with matters more fundamental than ingenuity of 
background. It was discovered, for instance, that titles should not 
anticipate action, which was precisely what had been learned about 
spoken words centuries earlier by stage folk. Of late years one has 
not seen much of the anticipatory title that is, anticipatory in 
that sense; but in the first decade or so of the present century, it 
was one of the commonest technical sins. A title would read some- 
thing like this "Next day John Smith took his wife out driving;" 
and the succeeding picture-sequence would forthwith show John 
Smith doing precisely that thing, with the inevitable boring effect 
on the audience of having done it twice. The title should not "give 
the snap away" should not, by telling too much, "take the edge off 
the story." 

Then it was found, too, that the decorated title background slowed 
the tempo by inviting, without concentrating, further attention. 
The outcome here was that the best practice eschewed decorated 
backgrounds in all titles that belonged expressly to the pictorial 
action "cut-in" titles, as they say using them only for "editorial" 
titles leading up to action, or for those covering lapses between se- 
quences or chapters of action. This explains the distinction drawn 
in the usual shooting script, of the silent picture days, between "titles' 
and "spoken titles." The former only were to be decorated. 

Nor was this all. The title writer began to learn that the words 
were very definitely related to the pictorial action, and that writing one 
was by no means like composing a sentence for a printed page. In 
Erich von Stroheim's interesting and in many respects notable 
picture Foolish Wives, there was a "lapse-of-time" title something 
like this: "Night . . . music . . . women's voices . . . surf . . . fra- 


grance . . . fireflies." No subject and predicate, no questions of 
syntax, no harrassing infinitives or metaphors just those items of 
the milieu necessarily omitted by the silent picture and here supplied. 

To the casual eye the title in its more advanced forms seemed more 
remarkable for what it left out than for what it said. Compression 
seemed the rule. One writer, Roy Summerville, on the scenario 
staff of old Triangle-Fine Arts, boasted occasionally that he was the 
first to use the three dots of elision to suggest the continuance of 
conversation not actually given on the screen; and there were other 
forms of editing words that forcibly reminded one of Henry Holt's 
famous advice to authors to practice their art by writing telegrams. 
There were also efforts to avoid the distractions of punctuation 
marks ; and if Roy Summerville should go down to fame for three 
asterisks, the present writer may claim the innovation of "no periods 
at ends of titles." In William De Mille's production of The Fast Set, 
made from Frederick Lonsdale's stage play Spring Cleaning, even 
the usual quotation marks were cut from spoken titles. The reason 
back of all this is the same that applies to newspaper headlines 
where punctuation also is frowned upon. Nothing there is permitted 
to interfere with reading the full meaning at the first glance. And 
in spoken titles the word uttered "trippingly upon the tongue" 
is of high importance. 

The title differs from the printed sentence in this other particular 
there can be no turning back to read it again. It comes but once 
in the ideal telling of the story, and then in the most effective succes- 
sion of bids for attention in which acting and scenery also figure. The 
title is now seen as essentially confirmatory of the pictorial action a 
supplement to things literally seen. By and large this endorses and 
carries on a long-standing practice of the stage where speech inter- 
prets the gesture, gesture there being commonly made first. This 
order of precedence, that the gesture is before the speech, is psy- 
chologically based on two points one that the eye is quicker than 
the ear, and that the spoken word, being oftenest a symbol of some- 
thing other than mere sound, requires more interpretation. 

But with the coming of talkies it is observable that this is no final 
statement of the case. Words are generally secondary to the pic- 
torial action; yet there are times when the words are quicker in 
point of time. Certainly it is more economical (to revert to a cele- 
brated anecdote of Barrie and Granville-Barker), to say in words 
that one has "a red-headed brother who drinks port in Shropshire" 


than to try to show it altogether in pictures. There indubitably is a 
time when the spoken word, despite its familiar character as a symbol 
of something else, comes to the forefront as the most effective of the 
available means to the given end ; and it is a very short-sighted direc- 
tor or continuity writer who does not seize upon it at that moment as a 
thoroughly legitimate means of artistic expression. 

Perfection of the motion picture title has brought about an econ- 
omy of words. This telegraphic character, however, is little more 
than has been attained by stage dialog, in which every phrase is 
fraught with meaning to just that extent that it may be comfortably 
absorbed by the audience not to do less with words but to do better. 
The tendency has been not to dispense with words, but to boil them 
down to elemental strength, just as the poet prunes and polishes his 
verse without meaning in the slightest degree that he is thereby re- 
linquishing his verbal medium. 


Turning from the symbolism of speech, one sees that there is a 
power of pure sound, proverbial and known first-hand to all music- 
lovers. There is the force of rhythm, used so effectively in the in- 
cessant beating of tom-toms off-stage in Austin Strong's celebrated 
play, The Drums of Oude, or even more closely knit into the plot of an 
early sound picture, The Dangerous Woman, with Milton Sills and 
Baclanova, where the savage ceremonies of an African tribe stir the 
sensuous nature of a white woman till she becomes a vampire. 
But even music tries mostly to express more than sound. One 
composition is The Awakening of Spring. Another is The March 
of the Wooden Soldiers. Still another is The Moonlight Sonata. 
Virtually all are interpretative of things other than what "delights 
the ear" alone. 

And yet even pure sound is not altogether new to the makers of 
titles. For many years they have been underscoring words for em- 
phasis, or having the words appear successively upon the screen in 
imitation of staccato utterance, or having speeches run in criss-cross 
to approximate the chatter of gossips, or having significant words 
like "War" and "Murder" and "Help!" grow from nothing till they 
fill the field, or having the cry "Police!" or "Fire!" in quivering letters, 
or having dialects suggested with occasional misspellings. Borrow- 
ings from the fine practice of typography have long given biblical 
utterances in the ecclesiastical black letter or "Old English," and 


growing discernment has uncovered the force that lies in delicate 
faces of type for plays of fragile sentiment, and more vigorous forms 
for virile stories. There has come about, it must be added, an all- 
around but peculiar style of lettering for titles that the type-founders 
have done the reciprocal compliment of casting in fonts. It is a 
generally round, open-faced letter, with heavy ceriphs, easy to pro- 
duce and to read and not seriously modified by varying laboratory 
developments of the film upon which it is used. 

Quite naturally it will be some time before the industry as a whole 
realizes the true affinity of motion picture titles and uttered speech 
naturally because in any radical departure, in art as in politics, the 
first overwhelming tendency is to throw out everything old pack 
and baggage. Nevertheless, and this should be clear by now, there 
are valuable benefits from the old to be cherished and enjoyed. So, 
before dispensing utterly with the long-serving title, its various forms 
should be scrutizined, each in complete detachment from the others, 
to see precisely what it has to give. 


One common form of title, long accepted on the screen, will seem 
quite unadaptable, and that is the editorial title in which the maker 
of the picture makes observations in his own person, without the 
intervening medium of any character. This title may say no more 
than "Dawn" or "Night" or "Home;" but it clearly is the injected 
comment of an outsider who is assumed, by the author's own terms, 
to be absent. 

Here, once again, it is easy for the purist in art to be over-nice in 
his discrimination. The editorial title has too many valuable uses 
to be abandoned just because the body of the picture is literally 
spoken. The opportunity to whisper, in a manner of speaking, into 
the spectator's ear, supplying him with just the right expression 
with which to describe and remember his moment of ecstasy, is 
rich in possibilities and no more illegitimate than the strains of music 
out of nowhere that are injected occasionally to build up the emotion 
of the scene. But there is a more virile function of the editorial 
title; and that is its service between chapters or sequences of action, 
bridging intervals of time or saving the periods of rest between intense 
emotional experiences from being gaps so great that the flow of inter- 
est falls through. 

From time to time in the regular theater the printed program has 


essayed this same last-named service, summarizing the preceding 
act and speculating, with rich promises of future pleasures, on the 
action to come; so there is an analogy. But the stage could never 
hope, in circumstances where the program is only occasionally read 
and then usually at inappropriate times, to attain the development 
of this device reached by the screen where everyone who attends the 
play must also, perforce, attend the title. 

Another proof is here of the truth that the possibilities of an art 
are realized best in the direction of its handicaps, and that its greatest 
weaknesses lie in what it finds easiest to do. When the printed pro- 
gram was first added to the facilities of the theater, theater folk fre- 
quently put into it important links in the plot not otherwise obtain- 
able. In course of time, however, misuses were curbed; and today 
the theater program is a mere list of players (found with difficulty 
in a farrago of advertising). For the fact is seen that, with a little 
ingenuity and patience, what the program gives so easily may be 
better given in the play itself. The time and place, the character 
names and identities and much more, are now "put across" by the 
action itself as it moves along. 

In this respect the talking pictures are following the stage example. 
They are tending to dispense utterly with printed descriptive matter 
once the play has started. The "iris out" and "iris in" shut off one 
scene and disclose another just the same, to all intents and purposes, 
as the stage curtain; and the characters in the second scene serve 
to tell how long the interval has been since the first and to what new 
place the audience has been transported. But however much better 
this practice may seem, the picture folk should not debar themselves 
wholly from advantages of the printed word. There indubitably 
are cases wherein a simple printed statement of the fact is far pref- 
erable to a strained expression of it by characters who would not 
reasonably do it, and the time for doing which throws the whole com- 
position out of balance. 

Of course it all depends on the circumstances. The artist's good 
taste and fine discrimination must prevail. The great objection 
to the editorial title is that it is the utterance of a person outside the 
story and therefore tends to break the spell of the play. Well, 
if the artist is an artist, he will know when he may resort to this ex- 
pedient and when he should not. He will know that even in moments 
of great dramatic stress it is sometimes not only possible but tre- 
mendously effective to put the reaction of the audience into words, 


or to help them to feel the reaction by articulating it for them. He 
will have less compunction about using the editorial title between 
"iris in" and "iris out" because at that time, as in the stage inter- 
mission, the spell of complete absorption has already been broken, 
the audience is once more aware that it is in a theater and grateful 
for the opportunity to recapitulate and reflect, and the editorial title 
may greatly assist their state of mind. Indeed, when intermissions 
between chapters, sequences, or acts are as brief as they are in screen 
practice, a predigested opinion of the case that has gone before, with 
the prospect of what is to come, may easily be essential to spectators 
who have had insufficient time in which to work out matters for 

It was found long ago that even films must have intermissions. 
The stage intermission, popularly supposed to be due to the necessity 
of changing scenes, is really for rest and thought ; and when so-called 
"super-features" began playing for the then supposedly unattainable 
two-dollar price on Broadway and appeared in about eighteen or 
twenty reels each to give money's worth, it was found necessary to 
full appreciation to break performance in the middle and give the 
patrons a quarter-hour or so to move around. 

As said before, the important working habit of mind is to ap- 
preciate verbal and printed speech for what they really are, without 
prejudice, and to employ them freely where they serve best. Out of 
this attitude will come the new art of talking pictures. 



Sutnary. Impurities in the water supply are classified as follows: Dissolved 
salts, suspended matter, dissolved extracts, dissolved gases. The action of each im- 
purity on development, fixation, and washing of films is treated. Methods of purify- 
ing water include distilling, boiling, filtering, and chemical treatment. Sea water, 
although not seriously harmful, should not be used excepting in an emergency. It is 
concluded that impurities in the water supply are not responsible for as many troubles 
as is usually supposed. 

Water is the most widely used chemical in the processing of motion 
picture film and it is important to know to what extent the impurities 
present in it may be harmful to the various operations and how these 
impurities may be removed. 

Impurities in Water. Excluding distilled water, rain water, and 
water from clean, melted ice or snow, the following impurities may be 

(1) Dissolved salts such as bicarbonates, chlorides, and sulfates of calcium, 

magnesium, sodium, and potassium. 

(2) Suspended matter, which may consist of: 

(0) Mineral matter such as mud, iron rust, or free sulfur. 
(6) Vegetable matter such as decayed vegetation. 
(c) Animal matter such as biological growths and bacteria. 
The suspended particles may be of colloidal dimensions in which case they 
are difficult to remove by filtration. 

(3) Dissolved extracts, usually colored yellow or brown, from decayed vege- 

table matter and the bark of trees. 

(4) Dissolved gases such as air, carbon dioxide, sulfur dioxide, and hydrogen 



Development. (!) If a developing solution is prepared with water 
containing calcium salts, a white precipitate consisting largely 
of calcium sulfite, but with some calcium carbonate, is apt to form on 

* Received by the Editor, February 27, 1931. 
** Research Laboratory, Eastman Kodak Co., Rochester, N. Y. 


438 J. I. CRABTREE AND G. E. MATTHEWS [J. S. M. p. E. 

mixing. In some cases a precipitate does not form immediately 
but a sludge 1 consisting of fine needle-shaped crystals of calcium 
sulfite separate out on standing (Fig. 1). Magnesium salts, unless 
present in excess, are not precipitated. Such a sludge or precipitate 
will settle out on the emulsion side of the film and cause spots. 2 
However, the white precipitate or sludge is harmless if allowed 
to settle, and if only the clear supernatant liquid is drawn off for use. 
The developer, of course, is robbed of sulfite and carbonate to the 
extent required to form the sludge or precipitate, but except in the 
case of developers of low alkalinity, this effect is negligible. Ex- 
( ^ periments have shown that the 

f "*^ quantity of calcium or mag- 

nesium salts occurring in aver- 
age natural waters in the United 
States is insufficient to produce 
an appreciable effect on the 
developing power of developers 
containing 0.3 per cent sodium 
carbonate by virtue of a lower- 
ing of the carbonate content. 3 
However, in the case of de- 
velopers containing borax, 
which are very sensitive to 
FIG. 1. Photomicrograph of developer slight changes in alkalinity, the 
sludge (calcium sufite) caused by presence presence of an appreciable 
of calcium salts in water supply. 

quantity of calcium salts would 

be sufficient to lower the alkali content, and due allowance for this 
should be made. 

Salts liable to be present, other than the above, are chlorides and 
bromides of the alkali metals which exert a restraining action. So- 
dium carbonate, which is present in certain alkaline waters, tends 
to speed up the action of a developer which is weak in alkali, al- 
though with the average developer the concentration of the alkali 
in the water used for mixing is insufficient to exert any appreciable 
effect. Developers mixed with water containing sodium or potas- 
sium sulfides will give bad chemical fog even if the sulfides are present 
in very small quantities. 

It is customary to add copper sulfate to certain water supplies 
at periodic intervals in order to kill vegetable and biological growths. 
While the presence of 1 part in 10,000 of the copper salt in a developer 


will cause aerial fog, 4 the concentration of the copper salt in the 
water supply usually is much lower than this. 

(2) A. Dirt and iron rust suspended in the developer solution 
often produce spots and stains. In the case of a pyro developer the 
iron is apt to combine with the pyro, forming an inky compound 
which imparts a bluish-red color to the solution although photo- 
graphically it is harmless. 

Particles of finely divided sulfur which give the characteristic 
opalescence to sulfur waters will cause fog, owing to the formation 
of sodium sulfide by interaction with the carbonate present in the 
developing solution. If the water is boiled, the colloidal sulfur usually 
coagulates, whereupon it may be separated by settling or filtration. 

B. Vegetable matter is usually precipitated by the salts present 
in the developer. 

C. Animal matter is usually precipitated on mixing the developer, 
but frequently biological growths and bacteria thrive in a developer 
and form a slime or scum on the walls of the tank. Some types of 
these growths act on the sulfite in the developer, changing it to so- 
dium sulfide which fogs the emulsion very badly. The sulfide is 
removed by developing some waste film in the solution or by adding 
a small quantity of lead acetate to the developer in the proportion of 
25 grains per gallon (0.4 gram per liter). 5 Tanks which show a ten- 
dency to accumulate slime should be scrubbed with hot water at 
regular intervals and then treated with a dilute sodium hypochlorite 
solution. 3 Suspended mineral, vegetable, or animal matter in general 
has usually no harmful effect on a developer, providing the mixed 
developing solution is allowed to stand and only the clear supernatant 
liquid drawn off for use. Preparing the developer with warm water 
tends to hasten the rate of settling of the suspended matter. 

(3) Extracts from decayed vegetable matter or the bark of trees 
usually discolor developing solutions but are often precipitated if 
the developer is prepared with warm water and allowed to stand. 
The staining effect of such extracts with motion picture film is usually 

(4) Water dissolves about 2 per cent of air at 70 F., and when 
a developing agent like hydroquinone is dissolved without the addi- 
tion of sulfite the oxygen present in the water combines with the 
developing agent, forming an oxidation product which is apt to stain 
the gelatin and fog the emulsion. Air in water occasionally collects 
on the film in the form of little bubbles or air-bells which prevent 

440 J. I. CRABTREE AND G. E. MATTHEWS [J. s. M. P. E. 

development and produce characteristic markings. 6 When de- 
veloping at high temperatures (above 80 F.) dissolved air often 
causes blisters. 7 

Mineral waters containing carbon dioxide rarely give much trouble, 
providing the water is boiled first in order to drive off the gas. If 
carbon dioxide is present in a developer in excessive amounts, it 
acts in the same way as dissolved air, producing bubbles and air- 

FIG 2. Appearance of scum on motion picture film 
after evaporation of drops of water containing dissolved 

bells on the film. Hydrogen sulfide gas will cause bad chemical 
fog in a developer but may be removed by boiling the water or by 
precipitating with lead acetate before mixing. 4 ' 5 

Fixation. Calcium and magnesium sulfites are soluble in acetic 
acid and therefore are not precipitated in fixing baths. Other dis- 
solved salts such as bicarbonates, chlorides, and sulfates are harm- 
less. Suspended matter such as dirt, iron rust, and certain types of 
vegetable and animal matter usually will coagulate and settle out on 
allowing the fixing bath to stand. 

Although most suspended substances have practically no effect 
on the photographic properties of fixing baths, the particles may settle 


on the film, locally retarding fixation, and produce spots and stains. 2 
Extracts from vegetable matter or dissolved gases do not affect the 
photographic properties of a fixing bath, but are liable to cause stains 
and blisters, and locally retard fixation. 

Washing. Dissolved salts often cause trouble by crystallizing 
on the film after drying, and although not always visible as crystals 
to the eye, they detract from its transparency (Fig. 2). Water which 
is free of dissolved salts also will cause markings on film providing 
it is allowed to remain in droplets on either side of the film during 
drying. 8 It is important therefore to remove thoroughly all excess 
water from the film before drying. This can be accomplished, (a) 
by draining thoroughly before applying a current of air ; (b) by swab- 
bing with wet absorbent cotton or chamois; and (c) by means of a 
pneumatic squeegee. 9 

Suspended mineral, vegetable, and animal matter usually produces 
a scum on film unless the gelatin surface is wiped carefully previous 
to drying. If the water used for washing is run into a large settling 
tank or is filtered before using for washing purposes, most of the 
suspended matter will be removed. 

Dissolved extracts produce stains which are very difficult to remove. 
Also, if the wash water is warm, dissolved gases will sometimes pro- 
duce blisters, especially if the film is not hardened sufficiently in the 
fixing bath. 3 

So far as is known, any small traces of impurities left in the 
gelatin coating of motion picture negative or positive film after 
drying, by virtue of the presence of these impurities in the wash 
water, are not liable to seriously impair the keeping properties of the 
films over a period of four or five years. However, films which are 
to be kept for long periods of time should be finally washed in dis- 
tilled water. 

The Preparation of Dye Solutions. Many dyes are precipitated 
out of solution by calcium or magnesium salts and alum. The 
precipitation is not always immediate and may occur only after 
standing for a few days. The properties of dyes with respect to 
their rate of penetration into gelatin or the rate at which they are 
mordanted are affected considerably by the presence of metallic 
ions, or acids, or bases, so that in color photography or when using 
desensitizers, impurities in the water are apt to produce anomalous 
results. Distilled water should be used whenever possible for pre- 
paring solutions of dyes. 

442 J. I. CRABTREE AND G. E. MATTHEWS [J. S. M. p. E. 


Distillation. Distilled water should be used whenever possible 
for mixing solutions. 

Boiling. Unless the water contains an excessive quantity of 
dissolved salts, it is usually sufficient to boil the water and allow it to 
settle. The supernatant portion then may be syphoned off or the 
solution filtered through fine muslin. Most colloidal vegetable 
and animal matter, comprising slimes and scums, coagulates on 
boiling and certain lime salts are changed to an insoluble condition 
and settle out. Dissolved extracts are not removed but dissolved 
gases are driven off by boiling. 

Filtration. Various types of water filters are available commer- 
cially, but these do not remove dissolved salts or colloidal matter 
unless the water has been treated previously with a coagulant. 

Chemical Treatment. The following methods of chemical purifica- 
tion may be adopted: 

(1) Potassium alum may be added in the proportion of 1 gram 
to 4 liters of water. This coagulates the slime which carries down 
suspended particles and clears the solution rapidly. Dissolved salts 
are not removed by this method. The small percentage of alum in- 
troduced into the water has no harmful effect on the solution when 
subsequently used for mixing developers and fixing baths. 

(2) A solution of sodium oxalate may be added until no further 
precipitate forms. This method removes the calcium and magnesium 
salts and coagulates the slime, although other dissolved salts are 
left in solution. Solutions of sodium phosphate and of sodium sulfite 
also may be used to precipitate calcium and magnesium. 

(3) Most of the commercial methods of softening water may be 
employed although such methods do not remove sodium and potas- 
sium salts. One of the most satisfactory methods consists in pass- 
ing the water through a tank containing sodium aluminum silicate 
(zeolite), which possesses the power of exchanging its sodium for 
the calcium and magnesium present in the water. 

Sodium aluminum silicate Sodium sulfate 


+ + 

Calcium sulfate Calcium aluminum silicate 

When the zeolite thus loaded with calcium and magnesium is 
washed in a strong solution of common salt (about 12 per cent) it 


exchanges its calcium and magnesium again for sodium and is thus 
regenerated, whereupon the chemical may then be used for further 

Calcium aluminum silicate Sodium aluminum silicate 


+ +. 

Sodium chloride Calcium chloride 


Sea water contains a relatively large proportion of soluble salts 
(about 3.5 per cent) and should not be used for mixing photographic 
solutions except in extreme emergencies when no other water is 
available. This is because the dissolved salts such as chlorides, 
bromides, and iodides, may retard the action of the photographic 
solution. When the supply of fresh water available is very small, 
sea water may be used for washing motion picture film, providing a 
last washing or soaking previous to drying is given in distilled or fresh 
water. 10 The film should be given a thorough washing later when 
plenty of fresh water is available. 

A chemical analysis of the water supply usually reveals very little 
concerning its photographic usefulness. It may be of some assistance 
in indicating the quantity of lime, oxalate, etc., to be added to remove 
dissolved calcium salts or to coagulate slimes. The quantity of total 
solids indicates if trouble from drying marks may be anticipated, 
while the presence of iron, hydrogen sulfide, or metallic sulfides 
should be regarded with suspicion. The only useful test is to pre- 
pare a developer with the sample and actually try it out compared 
with the same developer prepared with distilled water. 

Also a large drop of water should be allowed to dry on the film 
and the amount of residual scum observed. This will indicate the 
extent of the trouble to be expected if the water is not removed 
thoroughly before drying. 


If developing solutions are mixed with warm water (about 125F.) 
and allowed to stand over night, any precipitate or suspended matter 
will settle out and the clear supernatant liquid may be drawn off 
for use. The presence of calcium and other salts in the water supply 
is sometimes beneficial in so far as they tend to retard the swelling 
of the gelatin coating of the film during washing. This is of particular 
advantage in hot weather. 


The only impurities liable to cause serious trouble with developers 
are hydrogen sulfide or soluble metallic sulfides. With such water 
about 25 grains of lead acetate per gallon of developer (0.4 gram per 
liter) should be added before mixing. This removes the sulfides as 
lead sulfide and any excess lead is precipitated in the developer and 
settles out on standing. 

No trouble may be anticipated with fixing baths prepared with 
average samples of impure water providing the bath is clarified by 
settling before use. 

When washing photographic materials little trouble may be anti- 
cipated with uncolored water if the following precautions are taken: 
(a) remove all suspended matter by filtering, either by means of 
commercial filters or by placing two or three layers of cloth over 
the water outlet; (b) remove thoroughly all excess moisture from 
the film before drying. 

Water which is colored brown even after filtering, is very apt to 
cause staining of the highlights. It is a difficult matter to economi- 
cally remove the coloring matter from such waters and each case 
usually requires specific treatment. 


1 CRABTREE, J. I. : "The Nature of a Developer Sludge," Amer. Phot., 12 (1918), 
p. 126; B. J. Phot., 65 (1918), p. 87. 

2 CRABTREE, J. I.: "Stains on Negatives and Prints," Amer. Ann. Phot., 35 
(1921), p. 35; B. J. Phot., 68 (1921), p. 294. 

3 CRABTREE, J. I., AND MATTHEWS, G. E. : "Handling and Mixing Photographic 
Chemicals and Solution," Photo- Miniature, Nos. 200-201 (1927), Tennant & 
Ward, New York. 

4 CRABTREE, J. I.: "Chemical Fog," Amer. Ann. Phoi., 33 (1919), p. 20; B. J. 
Phot., 66 (1919), p. 97. 

5 DuNDON, M. L., AND CRABTREE, J. I.: "Sulfide Fog by Bacteria in Motion 
Picture Developers," Amer. Phot., 12 (1925), p. 96. 

6 CRABTREE, J. I., AND IVES, C. E.: "Rack Marks and Air-Bell Markings on 
Motion Picture Film," Trans. Soc. Mot. Pic. Eng., No. 24 (1925), p. 95; B. J. 
Phot., 72 (1925), p. 775; 73 (1926), p. 4. 

'CRABTREE, J. I.: "The Handling of Motion Picture Film at High Tempera 
tures," Trans. Soc. Mot. Pic. Eng., No. 19 (1924), p. 39; B. J. Phot., 71 (1924), 
p. 762. 

8 CRABTREE, J. I., AND MATTHEWS, G. E.: "Moisture Markings on Motion 
Picture Film," Trans. Soc. Mot. Pic. Eng., No. 17 (1923), p. 29; B. J. Phot., 71 
(1924), pp. 6 and 15. 

'CRABTREE, J. I., AND IVES, C. E.: "A Pneumatic Film Squeegee," Trans. 
Soc. Mot. Pic. Eng., XI, No. 30 (1927), p. 270. 

'HICKMAN, K. C. D.: "Washing Motion Picture Film," Trans. Soc. Mot. Pic. 
Eng., No. 23 (1925), p. 62. 


F. F. LUCAS** 

Summary. In the last ten years there has been developed at Bell Telephone 
Laboratories a new technic of high-power micrography, which has greatly extended the 
limits of useful magnification possible with a microscope. Since any extension of 
the limits of magnification of he microscope which is accompanied by a decrease in 
definition is useless, it was found necessary to increase the resolving power or defini- 
tion of the microscope. One way in which this can be done is by decreasing the wave- 
length of the light used. 

A microscope using ultra-violet light was developed about thirty years ago by Koehler 
of the Zeiss works. Due to various difficulties n operat ng it, this microscope soon 
became a scientific curiosity and was almost forgotten. About five years ago, a micro- 
scope of this type was obtained from the Zeiss works by Bell Laboratories, and the 
difficulties involved in the use of this nstrument were largely solved by the develop- 
ment of a mechanical method of focusing. With this microscope, it is possible to 
obtain crisp, brilliant images of metallurgical specimens magnified 5000 to 6000 
diameters. In studying the advantages and limitations of this microscope, it was 
found to be particularly applicable to the study of biological and medical specimens. 
Such specimens can be examined at high magnification under the ultra-violet micro- 
scope without the necessity of cutting, staining, or injuring them in any way. 

Until recently the microscope was regarded as an instrument which 
had yielded its basic store of knowledge. It was commonly believed 
that in order to learn more of the structure of matter, some new 
method of approach was necessary. During the course of the last 
ten years, however, there has been developed at Bell Telephone 
Laboratories, a new technic of high-power metallography. The 
limit of useful magnification has been extended so that crisp, brilliant 
images can be obtained by photographic methods at very high mag- 
nifications and with the full potential resolving power of the micro- 

The matter of the resolving power or definition of the microscope 
is of the greatest importance. When working at high magnifications, 
we are primarily interested in bringing out every detail with the 
utmost fidelity, rather than in obtaining a much more highly mag- 

* Presented at the Fall 1930 Meeting at New York, N. Y. 
** Bell Telephone Laboratories, New York, N. Y. 




[J. S. M. P. E. 

nified but greatly blurred view of the surface under scrutiny. For 
this reason any extention of the limits of magnification which is 
accompanied by a decrease in definition is useless and is frequently 
termed "empty" magnification (Fig. 1). Until eight or ten years 
ago, the apparent inability to secure from the microscope well- 
defined images at high magnifications led to the rather general 

acceptance of the theory that 
magnification in excess of 1000 to 

FIG. 1. Empty magnification. As 
can be seen from this picture, an in- 
crease in magnification is useless if ac- 
companied by a decrease in the resolv- 
ing power of the microscope. 

FIG. 2. Pearlite photographed with 
visible light. 

1500 diameters was of little value. Most work was carried out at 
very much lower magnifications. 

Resolving power is usually expressed in lines per inch and is 
defined numerically by the equation first derived by Abbe, one 
of the founders of the Zeiss works: 



in which TV is the number of lines per inch, (N.A.) is the numerical 
aperture of the objective used, and X is the wave-length of the light 
expressed in inches. In deriving this equation for the theoretical 
resolving power, it was assumed by Abb that the detail to be re- 
solved consisted of equally spaced lines in other words, a very fine 
ruling or grating. 

Metallographic specimens, however, do not consist of rulings but 
usually their structure exhibits the greatest variation in detail and 
in contrast. The microscope, then, is not dealing with a ruling, 

April, 1931] 



but under the conditions, its performance must be more along the 
lines of the ultra-microscope. It is possible to photograph very 
minute details of structure in metal specimens because these details 
are actually single particles or lines disposed in a field of maximum 
contrast. If there were a succession of these details aligned side- 
by-side and equally spaced, the indications are that Abbe*'s formula 
would hold. 

Sound picture engineers will readily recognize the analogy in the 
field of acoustics, where much of the theory is derived for steady-state 
sound waves and must, therefore, be modified in considering transient 
phenomena. Similarly, the formula for the resolving power of a 
microscope is derived from 
"steady-state" conditions, where 
"steady-state" applies, not to a 
time-sequence as in acoustics, but 
to a space-sequence considered 
across some hypothetical grating. 
At the end of this grating, it is 
obvious that ' ' end-conditions' ' 
rather than "steady-state" con- 
ditions must prevail. It is due 
to the effect of these "end-condi- 
tions" that a small isolated dot 
can be detected much more 
readily than Abbe*'s formula 
would have us believe. 

Another factor which enters is that of contrast. A black button 
on a piece of black velvet is not a conspicuous object but a white 
button is very conspicuous because of the contrast which is developed. 
The black velvet absorbs most of the light which falls on it but the 
white button reflects the most light, hence there is maximum con- 

Although Abbess formula applies strictly only to a hypothetical 
grating, it does show that resolution may be increased by decreasing 
the wave-length of the light used or by increasing the numerical 
aperture (or light-gathering power) of the objective. While either 
method may be used, we shall consider only the former at this time. 

When the problem of using light of shorter wave-length was first 
taken up at Bell Laboratories, it was found that a microscope for 
use with monochromatic light from the ultra-violet region had been 

FIG. 3. 

Pearlite photographed 
ultra-violet light. 


448 F. F. LUCAS [J. S. M. p. E. 

developed about thirty years ago by Professor Koehler of the Zeiss 
Scientific Staff. This microscope was intended for biological work 
and a number had been built and supplied to research groups 
throughout the world. Theoretically this microscope should 
furnish a resolving power nearly twice that of systems using visual 

FIG. 4. Ultra-violet microscope arranged for optical sectioning of living 
cells. The sound and fume hood is removed from the spark generating 
apparatus and the searcher eyepiece is in place above microscope. 

light. No one apparently could get it to work, however, and the 
apparatus soon became a scientific curiosity and was almost .for- 

About five years ago, we commissioned Zeiss to construct one 
of these ultra-violet microscopes for metallographic work. A photo- 
graph of this microscope is shown in Fig. 4. At the right is shown 
the spark generating apparatus with the sound and fume hood re- 
moved. The source of illumination is a quartz slit behind which 

April, 1931] 



is a spark gap. Cadmium electrodes are used because the cadmium 
spectrum has a line at 2750 A which is particularly suitable for ultra- 
violet work of this nature. At the electrodes the potential is 10,000 
volts secured from a primary source of 220 volts at 60 cycles by means 
of a step-up transformer. The light then passes through two quartz 

FIG. 5. Ultra-violet microscope with the sound and fume hood in place. 
The light emerges through the open window shown. This window is fitted 
with glass and excludes the ultra-violet light when closed, protecting the 
specimen except during the intervals of exposure. 

prisms and a collimator to emerge from the prism diaphragm in the 
form of a line spectrum. As originally designed for biological work 
the desired line enters a prism at the base of the microscope and is 
directed upward into the substage condenser. When used for 
metallurgical work the spark gap and associated optical system are 
elevated until the desired line is focused on the vertical illuminator, 
which is of the same general type used in ordinary metallurgical 



[J. S. M. P. E. 

microscopes. By means of a suitable optical system and a quartz 
plate contained within the illuminator, the ultra-violet light is de- 
flected downward to the specimen as in any metallurgical microscope 
using the Beck type illuminator. A schematic diagram of the optical 
system is shown in Fig. 6. It is interesting to note that all optical 
parts are made of quartz as glass is opaque to ultra-violet light. 

The spark generating equipment is mounted in a case located 
32 cm. from the microscope stool. It consists of a box support- 
ing a wooden cabinet, in the bottom of which are mounted two con- 













FIG. 6. Schematic diagram showing arrangement of optical system for ultra- 
violet microscope. 

densers and a safety spark gap. On top is a T-shaped, adjustable 
optical bench carrying a diaphragm, a prism table, a collimator, and 
the spark gap, as shown in Fig. 4 and in the diagram in Fig. 6. The 
electrode terminals have a screw adjustment and both electrodes are 
opened or closed simultaneously so that the gap will function cen- 
trally before a quartz slit mounted on the frame of the spark stand. 
Mounted on the end of the cabinet can be seen a small metal con- 
tainer, which houses a mercury vapor lamp. The flask mounted 
in front of the opening in the lamp housing is filled with a green filter 
solution yielding approximately monochromatic light and it also is 
used as a condenser. This lamp assembly can be used in two ways. 
Either it may be swung around to illuminate the vertical illuminator 
directly or it may be swung back so that a small mirror reflects the 


light through the prism diaphragm. By this latter arrangement it is 
possible to center the illumination with the mercury vapor light by 
aligning the optical system of the microscope with reference to the 
aperture in the prism diaphragm. 

The mercury vapor lamp has another important function to per- 
form. It provides a steady source of approximately monochromatic 
illumination, free from noise, by which the operator can focus the 
specimen, study its structure, and select a field as a preparatory step 
to photography with the ultra-violet illumination. Once the field 

FIG. 7. FIG. 8. 

Comparison of results obtained by visual light and ultra-violet photomicrog- 
raphy of a biological specimen. Fig. 7 was taken with the best apochromatic system 
(N.A. = 1.40) using visual light, while Fig. 8 shows an unstained section from the 
same paraffin block at 1500 X , using ultra-violet light. The sections were identical 
except one was stained and mounted on glass for the visual light microscope, and 
the other was unstained and mounted on quartz for the ultra-violet microscope. 

is selected with the mercury -vapor light, it must be refocused with 
the ultra-violet light. In this matter of focusing the instrument 
for ultra-violet light the main difficulty experienced in the operation 
of the ultra-violet microscope was encountered. Since ultra-violet 
light is invisible to the eye, the microscope cannot be focused by ordi- 
nary means, and some indirect method of focusing is, therefore, neces- 
sary. As originally designed a uranium eyepiece was provided 
which became fluorescent under the impact of the ultra-violet light 
and produced a fluorescent image of the surface under the microscope. 
The arrangement of the apparatus was such that if the image was 
in focus in the searcher eyepiece, it was also in focus thirty centimeters 



[J. S. M. P. E. 

B / 


c - ( 


D V 

C ^\ i 

r -S 

h N. 

^" J 

In actual practice, however, this arrangement does not work out 
very well, since the intensity of the illumination is not sufficient to 
secure an exact focus of the fluorescent image in the uranium eye- 
piece. One cannot tell with certainty whether the image is exactly 
in focus, coming into focus, or going out of focus. Therefore, to rely 
on the searcher eyepiece method of focusing with the present weak 
source of light means that it is almost entirely a matter of chance 
whether a well-focused picture be obtained. 

This problem was finally solved through the development of a 
special mechanical technic. By means of a circular scale and a 

pointer attached to the slow 
motion adjustment of the micro- 
scope, the focus of the microscope 
can be shifted in as small an 
amount as one-sixteenth of a 
micron. In using this attach- 
ment, an approximate focus is 
first obtained by means of the 
uranium eyepiece. It has been 
found that if four photographs 
are then taken with their planes 
one-quarter micron apart, at 
least one of the photographs will 
be in focus. 

With this technic developed, 
it became possible to obtain crisp, 
brilliant images at very high mag- 
nification, thus making the ultra- 
violet microscope unquestionably the most powerful microscope in 
the world. With it details as small as 300 atoms across (0.000003 
inch) can be detected and studied. Using this microscope, a series 
of studies has been made on iron and steel, on alloys for lead cable, 
and on many other metallurgical subjects of interest to the telephone 

From the technic developed for the examination of metals, there 
has developed another technic, also of very great value, but for use 
in a different field. As has been pointed out, the focus must be exact 
to within one-quarter micron, one one-hundred thousandth inch. 
Any optical system which will yield a sharply defined focal plane 
of about one-quarter micron should prove of great value in certain 

FIG. 9. Diagram illustrating optical 
sectioning of the ultra-violet micro- 

A transparent specimen such as a 
group of cells may be sectioned opti- 
cally. The focal planes may be spaced 
as closely as Vie micron generally a 
spacing of l n micron suffices. Detail 
above or below the focal plane does not 
interfere. Successive photographs 
taken on planes A, B, C, etc., give a 
progressive record of the structure. 

Magnifications as high as 5000 di- 
ameters result in crisp brilliant images 
with a high degree of resolution. 


types of work. For example, it appeared reasonable to suppose 
that we might substitute a transparent specimen for the opaque metal 
surface and, because of the transparency of the specimen, we should 
be able to photograph details of structure on different planes inside 
the specimen, without the necessity of cutting it. Obviously, if 
the focus is confined to a focal plane of inappreciable depth, detail 
above or below the exact focal plane should not interfere with the 

Especially in relation to the study of biological specimens (for 
which the ultra-violet microscope was first developed by Koehler), 
the value of this method of examination is obvious. By its means, 
it becomes possible, figuratively speaking, to actually place the micro- 
scope inside a living cell, microscopic in size. Not only does this 
enable us to take photographs at high magnifications of the interior 
structure of the cell without cutting or injuring it in any way, but 
it is also unnecessary to stain the cell to bring out structural details, 
as is usually necessary in the study of biological specimens by visual 
light. Details of structure are differentiated from one another by 
the different amounts of ultra-violet light which they will absorb. 
Unstained specimens, therefore, respond under the ultra-violet micro- 
scope much as stained ones will under a visual light microscope. 

The importance of this is evident as it is generally recognized 
that the structure of organic material is apt to be profoundly altered 
by the treatment required to prepare it for microscopic examination. 
In recent years, the trend of biological research appears to be toward 
the study of living material, avoiding the changes produced by fixa- 
tion, staining, and mounting. 

It may be argued that any cell removed from its normal living habi- 
tat and placed in an artificial medium is no longer a normal cell, 
even though it may be a living one. In some cases, well-justified 
doubts may be entertained as to whether the cell is actually alive. 
It is very difficult to decide matters in this borderland. Shall we 
answer by opinion, by careful laboratory observation, or by both? 
It can only be said that ultra-violet microscopy of living cells is 
in its infancy. Experimental observations on fresh and aged mate- 
rials have shown that changes do occur. In some cases, these changes 
are quite rapid; in others a surprisingly long time may elapse before 
any change or deterioration can be detected. Cells of the nervous 
system are most delicate of all, and we have found them more diffi- 
cult to work with than any other type of cell. Nevertheless photo- 



[J. S. M. P. E. 

graphs of this type of cell probably represent at least a close approxi- 
mation to normal. 

If we are to employ the ultra-violet microscope in researches of this 
type, two reservations must be kept in mind. The ultra-violet light 
itself must not have apparent injurious effects on the organisms, and 
the latter must not completely absorb the ultra-violet light, as any 
organism which does so obviously cannot be studied by these methods. 

Ultra-violet light of the intensity and wave-length used in this 




FIG. 10. Mouse tumor 1800 X. Optical sectioning. Ultra-violet micro- 
scope. A fixed but unstained specimen 

work appears to have little if any harmful effect on many types of 
living cells. It is true that some single-cell organisms are destroyed 
almost immediately; others of another species in the same mixed 
cultures appear mildly excited, and still others are apparently im- 
mune. From preliminary observations, it would appear that many 
living cell cultures may be exposed under the ultra-violet microscope 
as long as forty-five minutes, and, when returned to the incubator, 
they appear to grow and to suffer no ill effects from the exposure. 
One wonders what effect wave-lengths other than 2750 A would 
have on standard cell cultures. Will monochromatic light of one 

April, 1931] 



wave-length cause a living cell to disintegrate immediately and 
similar light of another wave-length have little or no effect? If 
so, then a very powerful way of dealing with cells will be at hand. 
To illustrate the application of the methods used, Fig. 11, A 
and B, show photomicrographs taken of cell structures. The tissues 

FIG. 11-A 

FIG. 11-B 

Embryos within the segments of a small tape-worm found within 
the body cavity of a mouse. The preparation was mounted in 
Locke's solution and was unstained. Fig. 11-A shows three optical 
sections at 500 X and Fig. 11-B shows three optical sections at 
1200 X. 

were taken from animals and transferred to physiological salt solu- 
tions. Cell smears were quickly made on quartz slides, a drop of 
the salt solution added and the preparation covered with a quartz 
cover slip, which was then sealed with vaseline to prevent evapora- 
tion from the preparation. The salt solutions were chosen with 
particular regard to their suitability for the purpose; in some cases 
body fluids of the cells themselves were used instead of the artificial 
salt solutions. 

456 F. F. LUCAS 

In closing it may be stated that the resolving power of a micro- 
scope, as computed from Abbe's formula, is a potential resolving 
power. Whether or not the full potentialities of the microscope 
are achieved depends on many other factors learning the best 
way to prepare the specimen for microscopic examination, for ex- 
ample. Structures are now being clearly resolved as aggregates, 
which less than four years ago, appeared practically structureless 
under the same conditions. Improvements in technic and in the 
preparation of specimens have enabled us to resolve these structures 
very clearly with the identical optical system which four years ago 
failed to accomplish the same end. There seems, therefore, to be every 
reason to believe that we can go much further with the microscope 
than we have gone up to the present time. 


C. E. BAER*' 

Summary. -^-The purpose of this paper is to set forth the various phases of the 
application of motion pictures as visual aids in teaching. It is pointed out that 
concrete experiences are a necessary prerequisite to the use of language and that 
educators, recognizing the prevalence of verbalism in schoolroom practice, are de- 
manding materials, devices, and methods to correct this weakness. Visual aids, 
properly used, equip a group with a common body of life experiences, useful as a basis 
of growth in knowledge. 

[By way of introduction to the paper, Mr. Baer presented three short film sub- 
jects of Eastman Teaching Films, having the titles Induced Currents, Energy from 
Sunlight, and Food and Growth. These films were presented in order to illustrate 
the subject matter used in films intended as visual aids in classroom instruction. 

It is the purpose of this paper to do at least three things: To show 
that concrete experiences are a necessary prerequisite to the use of 
language; that educators, recognizing the prevalence of verbalism 
in schoolroom practice, are demanding materials, devices, and methods 
to correct this weakness; and that visual aids, properly used, equip 
a group with a common body of life experiences useful as a basis of 
growth in knowledge. 

There are at least four approaches to a task of learning about a 
given thing, namely: (1) studying the thing itself; (2) studying a 
picture or representation of the things; (3) telling about a thing; 
(4) reading about a thing. The effectiveness of instruction is generally 
recognized as in the descending order of these approaches. This is 
due in part to the fact that the last two approaches presuppose some 
familiarity with the thing about which facts are to be presented. 
Furthermore, words of mouth or printed page are written or spoken 
symbols which have meaning to an individual only when he has within 
his experience the necessary sense perceptions which will serve as a 
basis for interpreting those symbols. 

* Presented at the New York Section Meeting, January 23, 1931. 
** Eastman Teaching Films, Inc., Rochester, N. Y. 


458 C. E. BAER [j. s. M. P. E. 

For example, the words "induced currents" take on meaning as 
the student associates with them a body of electrical- facts. Not 
till then do the words become useful symbols for ideas. The phrase 
"energy from sunlight" has only limited meaning to the student 
who has never studied transformation of energy in its relation to the 
ultimate source, the sun. A simple illustration of mental associa- 
tions which are connected with symbols appeared in an issue of a 
German publication: 

"Mr. X stands in front of his home late at night and cannot get 
in. He has forgotten the key, and he decides that this shall not 
happen to him again. He takes his handkerchief and carefully 
ties one of the four corners into a large knot. This is to remind him 
of the key tomorrow. 

"Mr. X knows nothing about psychology, but the course of 
action that he follows here is perfectly correct psychologically, and 
also effective. The following day he will take out his handkerchief 
at some time or other; then the knot will catch his eye, and im- 
mediately there will arise the image of the key in his mind. 

"But how can the view of the knot awaken the thought of the key 
when there certainly is no resemblance between the knotted forma- 
tion in the handkerchief and a key? 

"Because Mr. X was thinking so forcibly of the key while he was 
tying the knot, no other image but the one of the key arose during 
his recent inspection of the knot. 

"Between the occurrence 'knot' and the concept 'key' a relation 
has arisen so that the perception 'knot' almost coercively evokes the 
idea 'key.' In every-day language such a relation is called a 'com- 
bination of ideas.' The scientific expression for it is association. 

"Hundreds of these associations pass daily through the brain. 
Above all, it is in languages that associations occur, namely, connec- 
tions between word and meaning, whether the word is spoken and 
thus reaches the ear or comes before the eyes in written characters, 
whether we ourselves speak or write." 

Business men and men whose business is education have long 
recognized that words unsupported by a backing of experiences are 
symbols about as meaningless as a knot in a handkerchief is to a 
stranger who chances to see it. For mbre than three centuries the 
use of the concrete experiences has been advocated in the educa- 
tional systems of the great educators. In the 17th century Comenius, 
the great Moravian educational reformer, advocated learning from 


the world at large. He prepared a book, the Orbus P ictus, which 
first made use of illustration to visualize subject matter. From this 
book as a beginning has developed the modern pictorial text-book. 
Advertising experts, too, have learned through continued and care- 
fully studied experience that pictures and diagrams pay. 

In the 18th century Pestalozzi, the Swiss educational reformer, 
and Rousseau, the French essayist and philosopher, used visual 
materials to a great extent in their teachings. They advocated the 
return-to-nature doctrine, that life might be learned by living it. 
Thus, a study of the thing itself has become the basis of modern 
laboratory work and field trips. These are other forms of visual 

In the 19th century Froebel, the German educator and originator 
of the kindergarten system, stressed particularly those forms of 
instruction which used sight and touch. Meanwhile the invention 
of the photograph and photo-engraving processes have made pos- 
sible the illustration of magazines, newspapers, and books on a scale 
undreamed of heretofore. And out of the photograph have come the 
stereograph, the slide, and the motion picture film additional forms 
of visual aids. 

During the present century changes have come about in the United 
States which are greatly affecting educational procedures. Public 
schools and colleges are crowded with boys and girls with a wide 
range of native interests and abilities. Faced with large classes of 
pupils of mixed interests and abilities, teachers too frequently have 
followed the line of least resistance the use of the text-book without 
the use of many other approaches to learning. 

The effect of this lack of use of visual material has been very 
marked. In his book, Modern Methods in High School Teaching, 
Professor Douglass says, "Lessons are run through by teachers as 
if the mere speaking of words were bound to stimulate accurate 
and vivid images, or even worse, as if imagery were not of prime 
importance in learning. It would seem as if the objective of many 
teachers is the reciting of words which answer questions correctly, 
with little regard to whether or not the pupil has any adequate under- 
standing of the words recited." 

This evil of the classroom recitation is deep-seated and far-reaching 
in its effect on American school life. Educational reformers of the 
20th century, led by Professor John Dewey, have pointed the way 
to changes in the plan of school work which are removing this evil 

460 C. E. BAER [J. s. M. P. E. 

and some of its attendant maladies. To illustrate one of many 
desirable changes let me present a brief contrast of formal school 
work with socialized school work. 

In formal school work the pupil approaches tasks, memorizes, 
and recites, indifferent to and ignorant of values. The teacher, 
interested primarily in subject matter, sets these artificial tasks and 
too often is considered the foundation-head of all knowledge. 

In socialized school work, on the other hand, the teacher, inter- 
ested primarily in children, guides their natural activities and becomes 
a student with her pupils. The pupil explores his natural interests, 
thinks to a purpose, and expresses his thoughts accordingly. 

But this change in aim from formal to socialized school work de- 
mands revised methods, devices, and materials. It is obvious that 
visual materials properly selected and used should contribute to the 
accomplishment of this aim. In order to avoid statements of per- 
sonal opinion, I have selected quotations from a number of care- 
fully controlled investigations, which show that visual materials 
are effective aids in teaching. 

Dr. Freeman reported in Visual Education that "the function 
of visual aids is determined by the nature and purpose of the in- 
struction. The purpose of instruction at one time is to lay the founda- 
tion for thought, reflection, generalization, application. This 
foundation consists in direct experience with material objects. At 
another time the purpose is to build upon this foundation the super- 
structure of thought .... The evidence is that pictures are an 
invaluable means of getting certain kinds of experience of a concrete 

Knowlton and Tilton found in the teaching of American history 
that motion pictures "contributed materially to the gaining and 
retention of worth-while knowledge, particularly of knowledge of 
inter-relationships, other than time." In this experiment it was 
found that motion pictures "produced more pupil participation in 
classroom discussion," and "caused the pupils who saw them to read 
voluntarily more supplementary history reading material than did 
the orally-instructed classes." 

Wood and Freeman concluded as a result of the Eastman experi- 
ments in teaching geography and science that the motion picture 
enables "pupils to get clear-cut and correct notions of the physical 
aspect of the world. This is its immediate function. The material 
which is to be included in the film should be selected with this in view. 


The ultimate purpose of securing a clear-cut, concrete idea, of course, 
is to promote exactness and soundness in thinking. The material 
which is presented to the pupil, then, should be that material which 
is necessary in order to furnish him with this foundation. The 
selection of material, of course, and the manner and context in which 
it is presented, must be determined by the ultimate purpose. This 
does not mean, however, that an attempt should be made to distort 
the films from their natural purpose and make them into a means of 
teaching abstractions directly. Mankind has invented an instru- 
ment of abstract thought which is vastly superior to the use of ob- 
jects, or of pictures of objects. This instrument is language. It is 
not the business of the films to supplant language. It is their busi- 
ness to give the pupils such direct experience as will give language 
rich and clear-cut meaning." 

The presentation of a film gives a group of people, as a necessary 
start in the process of learning, a common mental content. A class- 
room film to be a teaching film must be able to marshall pictorial 
facts, and present them in proper order so that the group as a whole 
has assembled before it a body of information out of which real 
knowledge may be gained. With pictures, "talk" is some evidence 
of knowledge on the part of the pupils. The teacher and every 
member of the class is able to judge the value of verbal responses, 
and loses little time in the progress of discussion. In ordinary class- 
room practice so much time is wasted in the interpretation of sym- 
bols, in collecting and agreeing upon facts that little time is left 
for the development of the lesson. Motion pictures shorten the 
time necessary for presentation of essential facts. The time thus 
salvaged may be used in that most important aspect of teaching, 
assimilation or integration of the facts through discussion in a so- 
cialized recitation. It is from this assimilation of new experiences 
with old experiences that knowledge grows. So much time is spent 
in collecting the lumber and building the scaffold of the building that 
little time is left to work on the building itself. 

In conclusion: Films should be used for definite teaching purposes; 
films furnish concrete experiences of a total situation in place of in- 
adequate and partial imagery; films furnish an objective basis for 
verbal symbols; films equip a group with a common body of ex- 
perience held in forefront of attention ; films bring school more closely 
in touch with current community life by bridging the gap which 
exists between the school and the world; films give an interest in a 

462 C. E. BAER [J. S. M. P. E. 

new topic and an encouraging start through the use of interesting 
and vivid material; films are effective aids in summarizing a given 
topic or phase of work. 

Teachers should prepare for the presentation of a film by a 
careful preview and the preparation of an appropriate lesson plan. 
Pupils should be given a definite assignment in advance of a film 
showing. Presentation of a film lesson should be followed by a 
period of discussion in which the new elements of learning are inte- 
grated into the old. 


PRESIDENT CRABTREE: What are your thoughts on the use of sound pictures 
for educational purposes? 

MR. BAER: What the possibilities are for sound pictures we do not know. 
Experience has already shown what can be done with the silent picture. 

PRESIDENT CRABTREE : We are interested in this, of course, from an economic 
standpoint. Have you any hopes that in the future, schools will be able to get 
the necessary appropriations for this form of education? 

MR. BAER: If you refer to sound equipment, I cannot answer your question, 
as we have had no experience in that direction. If your question refers to the 
comparatively cheap silent equipment, this depends on whether educational 
directors become sufficiently aware of the ultimate economies in learning that 
result from the use of concreteatnaterials to demand a proper place for films in 
the school budget. We are very hopeful, as things are developing, that the use 
of motion pictures will become more general as time goes on. Schools quite 
generally are purchasing 16 mm. projectors as standard classroom equipment. 

PRESIDENT CRABTREE : Would schools prefer to buy or rent the films? 

MR. BAER: As a practical school man, I would prefer to have the films in a 
form and place where they could be used as readily as a supplementary text-book 
might be used. To assure such convenience, ownership of films by a board of 
education is necessary. Otherwise, films may be used indifferently. 

Eastman Teaching Films, Inc., has been marketing its product only a little 
over two years. The sales the first year were all that the company anticipated, 
and were much greater the second year. The experience thus far justifies the 
belief that the film has a permanent place in classroom aids. There is a develop- 
ing sentiment among teachers, indicating the general use of films in the schools of 
the country. 

MR. ROSENBERGER: Are films made for use in medical education? 

Mr. BAER: Eastman Teaching Films, Inc., has a series of medical pictures for 
professional use, which may be either purchased or rented. The pictures shown 
this evening were on 16 mm. film, prepared as instructional aids for classroom use 
under the supervision of a teacher. They are samples from our growing library. 
In our classroom series we have about 150 subjects classified roughly under the 
headings geography, health, science, and nature. 

MR. ROSENBERGER: What is the life of the 16 mm. film made on safety stock 
as compared to the ordinary 35 mm. film? 


PRESIDENT CRABTREE: If the film is stored in a fairly moist atmosphere 
having a relative humidity about 70 per cent, its life is of the order of several 
hundred runs. If it is stored in a dry atmosphere, it will tend to become brittle, 
and the life will be reduced considerably. If the film has become dry and brittle, 
it should be reconditioned by re-humidifying, whereupon its good wearing quali- 
ties will be restored. The projection life depends also upon the mechanical 
condition of the projector. 

CHAIRMAN PALMER: Are teachers receptive or antagonistic toward films? 

MR. BAER: Experience indicates that teachers are very receptive to the use 
of motion pictures as a tool of instruction in the classroom. 

MR. SHEA : Would you care to say anything regarding the pedagogical limita- 
tions of films? I viewed these pictures as an adult, and from the point-of-view 
of one not too familiar with the teaching of children. 

Consider the possible incompleteness of ideas represented symbolically in 
cartopn form; the possibly distractive character of much that is in a motion 
picture which does not concern the central idea but which is necessary to reality; 
the rapid change from one idea to another in the picture. 

MR. BAER: Visual aids, motion pictures or otherwise, are aids to instruc- 
tion, elements in a teaching procedure which looks toward the integration of 
concrete ideas into a form called knowledge. It is therefore presumed that be- 
fore the picture has been shown there have been certain preliminary stages of 
instruction and that the presentation of the film is but one step in the entire 
process. It is necessary to move rapidly from one scene to another in order to 
bring the necessary amount of concrete material to the pupil's attention. 

However, it is the duty of the scenario writer and the film editor to so set up 
scenes and situations that the flow of pictures is progressive. Occasionally a 
title is inserted to direct attention, and sometimes an observation-directing 
device, such as an arrow. After a picture has been presented to a class, it usually 
happens that about as many questions have been raised as have been answered. 
Pedagogically, this is a good thing. 

To what extent thought-provoking situations should be raised is a matter 
which requires study ; that is part of the art of teaching. In an artfully constructed 
film each step will be built sufficiently high that proper mental effort will be 
required to surmount it. 

MR. SHEA: That rather confirms the thought that motion pictures, instead 
of replacing the teacher to any extent, demand at least as intelligent a type of 
teacher as we have had in the past. 

MR. BAER: May I say, more so. She has to learn how to handle a new tool; 
however, the outcome of the instruction will be much more satisfying after that 
effort has been expended. The children, as has been proved by repeated experi- 
ments, get more out of it and put more into it. 

MR. BEGGS: Is the classroom in darkness when the pictures are projected? 

MR. BAER: The room should be as dark as is conveniently possible. This 
applies in general to all projection. Without an adequately darkened room, 
some of the action shown on the screen may be obscured by direct light falling 
upon the screen. Common forms of opaque window shades are quite satisfactory, 
and are simple and inexpensive. 

MR. BEGGS: We occasionally ask about this, and seem to feel that it would 

464 C. E. BAER [J. s. M. P. E. 

be better if the pictures could be shown under normal room-lighting conditions. 

MR. NIXON: Some educators favor still pictures, which do not require as 
much illumination as do motion pictures. It is common practice to project still 
pictures with merely a subdued light. The question of discipline has also been 
discussed; however, if the teacher presents the subject matter in an interesting 
manner, this may be an item of only minor importance. 

MR. BAER: I have as yet seen no case of discipline arise where films were 
systematically used in the regular classroom. It is my impression that when 
children are looking at motion pictures they become a part of the action on the 
screen; they put themselves right into it. This is especially true where the 
human element in the picture is prominent. 

MR. ROSENBERGER: Are the films supplied by the Eastman Teaching Films, 
Inc., accompanied by a manual for the teacher? 

MR. BAER: There is included with each film, a teacher's guide or manual 
which contains a summary of the research that the scenario writer has compiled 
in working up the contents of the picture, both scene by scene and on the subject 
as a whole. It includes suggestions for reorganization review, called problems, 
and selected references for teachers. 

MR. WHITMORE: What is the average number of titles in these films? 

MR. BAER: Energy from Sunlight, which you have seen, contains twenty-one 
titles, in which a total of 128 words are used. This film has more titles than most 
of our pictures. The tendency is to reduce the number of titles or subtitles to 
the smallest number that is consistent with the need for thought-directing state- 
ments. Food and Growth was for the younger grade school children, Energy 
from Sunlight was for children in junior high school, and Induced Currents was 
for the upper junior high school and senior high school. 

MR. WHITMORE: Where do you find the best field for these films? 

MR. BAER: The large city schools have the most complete programs of visual 
education, and have directors of visual education and plans for supervision and 
distribution of films. Perhaps as good an example as any is Pittsburgh. How- 
ever, considering the total sales, it is surprising to what extent the smaller schools 

Sometimes the most wide-awake executives are in the smaller places. But in the 
larger places, where there are worked-out plans and policies, appropriations have 
been set aside for films. Of course, big programs usually mean big sales. 

MR. SATTLER: Are the subjects usually complete in one reel? 

MR. BAER: Almost without exception. Each subject is so divided that it is 
not necessary to present the whole reel. It may be presented section by section 
at appropriate times. For instance, Energy from Sunlight might be split up into 
the different sections, viz., heat, water-power, wind-power; the picture is 
frequently presented this way. 

MR. SATTLER: Might not a school have two machines to permit changing 
from one subject to another? 

MR. BAER: That would not be necessary in a schoolroom. One reel, fifteen 
minutes of motion pictures, should be ample for several periods of study and 

CHAIRMAN PALMER: Is it not possible that the picture could be made more 
interesting if the titles were given with sound instead of having the children read 


them; this would not spoil the continuity. Furthermore, the photographic 
quality seems to be quite an important matter. The children should be shown 
pictures of only the highest photographic quality. 

PRESIDENT CRABTREE : These pictures were made not only by the cameramen 
hired by Eastman Teaching Films, Inc., but by cameramen in all parts of the 
world. They are good and bad in spots. Some of the prints were made from 
duplicate negatives; this is because it is not always possible to buy the negatives. 

Getting back to the economics of the situation, Mr. Eastman is responsible 
for Eastman Teaching Films. He felt, many years ago, that there was a need 
for education by means of moving pictures, and laid aside a large sum of money 
to experiment along these lines. The experiment turned out successfully, and it 
has now got to the stage where it is necessary to make a business out of it, 
unless some other philanthropist comes along and supplies the schools with films 
at a loss. How can we extend the use of these films by the schools so that the 
utmost benefit can be derived from them? We, as engineers, can do our part by 
devising apparatus and films that will be cheaper. We should also devise better 
means of distribution. 

MR. MANHEIMER: Is there any real opposition to this method of education? 
Are any educators opposing the use of motion pictures in schools? 

MR. BAER: I know of no opposition; there may be some inertia; you know 
education moves quite slowly. 

MR. WEBB: I believe that titles should be edited by one who is teaching 
children and who has their viewpoint, and could word the titles in terms which 
they could understand. 

MR. BAER: To which picture are you referring? 

MR. WEBB : To Food and Growth. The film needs explanation by the teacher, 
rather than by titles. The titles spoil the continuity. 

MR. BAER: I have already stressed the need for active classroom discussion 
following the presentation of a film. Not uncommonly so many questions de- 
velop spontaneously that a repeat showing of the picture is necessary as early as 
the second day. Eagerness of this sort begets knowledge. The picture referred 
to was titled by a group of practical teachers. It is worth while for a child to 
get a vivid impression of how a scientific study of food and growth is carried out. 
The film shows a type of controlled experiment which fundamentally is so simple 
that a child under supervision might be able to perform it. 



[J. S. M. P. E. 



RCA Photophone, Inc., 366 N. 
Stanley Ave., Los Angeles, Calif. 

16 Rue Roussel, Paris, XVII, 


Kodak Pathe Research Laboratory, 
30 Rue des Vignerons, Vincennes 
(Seine), France. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

British International Pictures, Ltd., 

Elstree, Herts, England. 

Alexander Film Industries, Inc., 

Colorado Springs, Colo. 

Consolidated Film Laboratories, 
Inc., 933 Seward St., Hollywood, 

Capitol Stage Lighting Co., 626 

Tenth Ave., New York, N. Y. 

University of Toronto, Toronto, 

Ont., Can. 

4066 Duquesne Ave., Culver City, 


Carter Sound Equipment Co., 1500 
Union Ave., S. E., Grand Rapids, 

Art Film Studios, Inc., P. O. Box 

418, Cleveland, Ohio. 

New England Theaters Operating 
Corp., 19 Milk St., Boston, Mass. 

Akeley Camera, Inc., 175 Varick St., 
New York, N. Y. 


Ashcraft Automatic Arc Co., 4214 
Santa Monica Blvd., Los Angeles, 
ATKINSON, S. C. (4) 

Regina Photo Supply, Ltd., 1924 
Rose St., Regina, Sask., Canada. 


Ontario Govt. M. P. Bureau. Parlia- 
ment Buildings, Toronto, Can. 

Canadian Government Motion Pic- 
ture Bureau, Ottawa, Can. 

20 McEldowny St., Chicago Heights, 


RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

Imperial Dry Plate Co., Ltd., 
Cricklewood, London, N. W. 2, 
BAKER, W. R. G. (M} 

RCA Victor Co., Inc., Camden, N. J. 

Brooklyn Edison Co., 380 Pearl St., 

Brooklyn, N. Y. 
BALL, J. A. (M) 

Technicolor Motion Picture Corp., 
823 N. Seward St., Hollywood, 

Moving Picture Theater Managers 
Institute, 315 Washington St., 
Elmira, N. Y. 

614 10th Ave., Belmar, N. J. 

* (M) Active Member. 
(A) Associate Member. 

April, 1931] 




52 Howburg Rd., Newhead, London, 

S. E. 15, England. 

801 Great Republic Life Bldg., Los 

Angeles, Calif. 

N. Y. Institute of Photography, 
10 West 33rd St., New York, N. Y. 

Western Electric Co., 120 West 41st 

St., New York, N. Y. 

Metropolitan Theater, Boston, 


Carl Zeiss, Inc., 485 Fifth Ave., New 

York, N. Y. 

Bass Camera Co., 179 W. Madison 

St., Chicago, 111. 

Lighting Service Dept., Canadian 
General Electric Co., Ltd., 212 
King St., W., Toronto, Canada. 

RCA Photophone, Inc., 153 E. 

24th St., New York, N. Y. 

Colortone Pictures, Inc., 1996 Boule- 
vard E., Hudson Heights, N. J. 

Carl Zeiss, Inc., 485 Fifth Ave.* 

New York, N. Y. 

National Theater Supply Co., 372 

Pearl St., Buffalo, N. Y. 

420 Clinton Ave., Brooklyn, N. Y. 

Assoc. of Mot. Pict. Producers, Inc., 
5504 Hollywood Blvd., Holly- 
wood, Calif. 

Publix Theaters Corp., Paramount 
Bldg., New York, N. Y. 


166 Wardour St., London, W. 1, 


23-30 Newtown Ave., Astoria, L. I., 

N. Y. 

Research Lab., General Electric Co., 

Schenectady, N. Y. 

Warner Bros. Industrial Films, Inc., 
220 W. 42nd St., New York, 
N. Y. 

Capitol Theater, Windsor, Ont, 


Room 810, 1482 Broadway, New 

York, N. Y. 

Ste. Francaise Cinechromatique 9- 
11, Blvd. de Villiers, Neuilly, 
Seine, France. 

79 Blvd. Haussmann, Paris, France. 

Film Lab., Inc., 115 W. Austin Ave., 

Chicago, 111. 

Compagnie Radio Cinema, 79 Blvd. 

Haussmann, Paris, 8e, France. 

Kiddle, Margeson & Hornidge, 511 

Fifth Ave., New York, N. Y. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

Astro-Gesellschaft m. b. h., Lahn- 
strasse 30, Berlin-Neukolln, Ger- 

RCA Photophone, Inc., 7000 Santa 
Monica Blvd., Hollywood, Calif. 

British Lion Film Corp., Beacons- 
field, Bucks, England. 



[J. S. M. P. E. 


Drem Products Corp., 152 W. 42nd 

St., New York, N. Y. 

Blackwell Film Prod. Co., 1014 

Jackson St., Toledo, Ohio. 

Eastman Kodak Co., 343 State St., 

Rochester, N. Y. 
BLAKE, E. E. (A) 

Kodak, Ltd., 63 Kingsway, London, 

W. C. 2, England. 
BLANEY.'J. M. (M) 

Colorcraft Corp., 122 E. 42nd St., 

New York, N. Y. 

1362 N. Fairfax Ave., Hollywood, 

BLYTHE, S. C. W. (-4) 

New Era Productions, Ltd., 26-27 
D'Arblay St., London, W. 1, Eng- 

93, Prinzregentstrasse, Berlin-Wil- 

mersdorf, Germany. 

Compagnie Bol S. A., Rue Du Leo- 
pard, Geneve- Acacias (Suisse). 

Agfa Ansco Corp., Johnson City,N.Y. 
Agfa Ansco Corp., Camera Works, 

Johnson City, N. Y. 

18 Kenmare Road, Larchmont, N. Y. 

Gainsborough Pictures, Ltd., 58 War- 
dour St., London, W. 1, England. 
1207 N. Mansfield Ave., Hollywood, 


Ontario Govt. M. P. Bureau, Parlia- 
ment Bldgs., Toronto, Can. 

Jam Handy Picture Service, 2900 
E. Grand Blvd., Detroit, Mich. 


1301 Sixth Ave., Apt. B., Tacoma. 


2140 Champa St., Denver, Colo. 

407 Eleventh St., Gothenburg, Neb. 

Consolidated Film Industries, Inc., 

Fort Lee, N. J. 

4425 John R St., Detroit, Mich. 

1041 N. Formosa St., Hollywood, 


528 Riverside Dr., New York, N. Y. 
BROEG, W. E. (A) 

Standard Brands, Inc., 20th & 
Venango Sts., Philadelphia, Pa. 

RCA Victor Co., Inc., Camden, N. J. 

704 S. Spring St., Los Angeles, Calif. 

Williamson Film Printing Co., Ltd., 

Barnet, Herts, England. 

Fox-Hearst Corp., 460 W. 54th St., 

New York, N. Y. 

R. F. D. No. 1, Box 33, Ellsworth 

.Falls, Me. 

1609 West 40th St., Oklahoma City, 


Carrier Engineering Corp., 39 Cort- 
landt St., New York, N. Y. 


Theatre Lighting & Equip. Co., 
255 Golden Gate Ave., San Fran- 
cisco, Calif. 
BUREL, L, H. (A) 

66, Rue Lepic, Paris, France. 

April, 1931] 


, 469 


Camera Dept., Paramount Publix 
Corp., 5451 Marathon St., Holly- 
wood, Calif. 

P. O. Box 132, Stratford, New 


RQA Radiotron Co., 415 S. 5th St., 

Harrison, N. J. 

Burnett Timken Research Labora- 
tory, Alpine, N. J. 

3034 Leland .Ave., Chicago, 111. 
BURNS, S. R. (M) 

Fox Film Corp., 444 W. 56th St. 

New York, N. Y. 

1306 S. Michigan Ave., Chicago, 111. 

Kodak A. - G., Friedrichshagener- 
strasse 9, Berlin-Copenick, Ger- 

1030 W. 49th St., Los Angeles, 


General Electric Vapor Lamp Co., 
Hoboken, N. J. 


National Lamp Works, 441 Lexing- 
ton Ave., New York, N. Y. 

RCA Photophone, Inc., 3932 S. 

Lincoln St., Chicago, 111. 

Manhattan Beach, N. Y. 

Film Sound Corp., 1825 E. 18th St., 

Cleveland, Ohio. 
23 Ogwen St., off W: Derby Rd., 

Liverpool, England. 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 


United Research Co., 41-40 Harold 
Ave., Long Island City, N. Y. 

Escar Motion Picture Service, Inc., 
10008 Carnegie Ave., Cleveland, 

Picture Production Dept., Seiberling 

Rubber Co., Akron, Ohio. 
CARSON, W. H. (M) 
Agfa Ansco Corp., Birighamton, 

N. Y. 

1254 East 31st St., Brooklyn, N. Y. 

954 W. 47th St., Los Angeles, Calif. 

38 Mechanic St., New Haven, Conn. 

Eastman Kodak Co., 6706 Santa 
Monica Blvd., Hollywood, Calif. 
Old Short Hills Road, Short Hills, 

N. J. 

Technicolor Mot. Pict. Corp., 1006 
N. Cole Ave., Hollywood, Calif. 

420 Victoria St., Nelson, B. C. 
8827 Woodhaven Blvd., Wood- 
haven, L. I., N. Y. 

22 Rue de Civry, Paris, XVI, France. 
J. Frank Brockliss, Ltd., 58 Great 
Marlborough St., London, W. 1, 

Eastman Kodak Co., 190 Platt St., 
Rochester, N. Y. 

ClFRE, J. S. (M) 

National Theater Supply Co., 211 

Columbus Ave., Boston, Mass. 

60 Grand St., New York, N. Y. 



[J. S. M. P. E. 

CLARK, D. B. (M) 
Wm. Fox Studios, 4601 Sunset Blvd., 

Hollywood, Calif. 

Weston Electrical Instrument Corp., 
614 Frelinghuysen Ave., Newark, 
N. J. 

Pathe Studios, Culver City, Calif. 

Clark-Cine Service, 2540 Park Ave., 

Detroit, Mich. 

Kodak, Ltd., Wealdstone, Middle- 
sex, England. 
9430 46th Ave., Elmhurst, L. I., 

N. Y. 
CLAYTON, ROY 3. 04) 

Metropolitan Sound Studio, Holly- 
wood, Calif. 

COFFMAN, J. W.'(Af) 

Audio-Cinema, Inc., 2826 Decatur 

Ave., New York, N. Y.. 

Paramount Publix Corp., 1501 

Broadway, New York, N. Y. 

Atlantic Gelatin Co., Hill St., Wo- 

burn, Mass. 

Kodak, Ltd., Wealdstone, Middle- 
sex, England. 
Rabun Theater, Clayton, Ga. 


Fox Film Corp., 441 W. 55th St., 
New York, N. Y. 


Colorfilm Corp., 130 W. 46th St., 

New York, N. Y. 
Bausch & Lomb Optical Co., 635 

St. Paul St., Rochester, N. Y. 

Eastman Kodak Co., 343 State 
Street, Rochester, N. Y. 

Kodascope Libraries, 33 West 42nd 

St., New York, N. Y. 

1819 G. St., N. W., Washington, D.C. 

Pathe News, 1023 S. Wabash Ave., 

Chicago, 111. 
J. E. Brulatour, Inc., 6700 Santa 
Monica Blvd., Hollywood, Calif. 

Academy of Motion Picture Arts & 
Science, 7046 Hollywood Blvd., 
Hollywood, Calif. 
Eastman Kodak Co., 343 State 

Street, Rochester, N. Y. 

Paramount Publix Corp., 35-11 35th 

Ave., Long Island City, N. Y. 
COZZENS, Louis S. (M) 

DuPont Pathe Film Mfg. Co., Par- 

lin, N. J. 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 

Bennett Film Labs., 6363 Santa 
Monica Blvd., Hollywood, Calif. 

Sound Beach, Conn. 

Powers Cinephone Equipment Co., 
723 Seventh Ave., New York, N. Y. 

605 W. 112th St., New York, N. Y. 

Multicolor Films, Inc., 201 N. Occi- 
dental Blvd., Los Angeles, Calif. 

5923 Beach Drive, Seattle, Wash. 

78 H Street, Salt Lake City, Utah. 

Theater Enterprises, 601 Guaranty 
Bldg., Hollywood, Calif. 

April, 1931] 




131 Gladstone Ave., Windsor, Can. 

12 Maiden Lane, New York, N. Y. 

Cummings Labs., 23 W. 60th St., 

New York, N. Y. 

5894 Enright Ave., St. Louis, Mo. 

Agfa Raw Film Corp., 1328 Broad- 
way, New York, N. Y. 

RCA Victor Co., Inc., Camden, N. J. 

Box 1614, Station A, Chattanooga, 


Eastman Kodak Co., 343 State 
Street, Rochester, N. Y. 


Societe Technique d'Optique et de 
Photographic, 28 Rue Boissy 
d'Anglas, Paris, France. 

Material Cinematographique, 111, 
113 Rue StMaur Paris, Xle, 

Kerite Insulated Wire & Cable Co., 

Seymour, Conn. 
34 Cheestey per N6, Apt. 8, Moscow, 

U. S. S. R. 
DASH, C. C. (M) 

Hertner Electric Co., 12690 Elm- 
wood Ave., Cleveland, Ohio. 
Fox-Hearst Corp., 460 W. 54th St., 

New York, N. Y. 
Roy Davidge Film Laboratories, 
6701 Santa Monica Blvd., Holly- 
wood, Calif. 
DAVIDSON, L. E. (.4) 
Visual Demonstration System, Inc., 
259 Delaware Ave., Buffalo, N. Y. 


Pathe of France, Ltd., 5 Lisle St., 

London, W. C. 2, England. 
DE AMICIS, D. S. (4) 

Paramount Publix Corp., Paramount 

Bldg., New York, N. Y. 

11749 Van Owen Ave., North Holly- 
wood, Calif. 

Materiel Cinematographique, 111, 
113 Rue StMaur, Paris, France. 

Roma- Villa Medioevale Torlonia, 
via Lazzaro Spallanzani la, Rome, 

Studios Cineromans, 20 Av. du gen- 
eral Gallieni, Joinville, France. 

1737 Whitley Ave., Hollywood, 


De Frenes Co., 60 N. State St., 

Wilkes-Barre, Pa. 
Menlo Park, Calif. 

Paramount Publix Corp., Astoria, 

L. I., N. Y. 

Dennison Film Processing Co., 729 
Seventh Ave., New York, N. Y. 
Famous Players Canadian Corp., 61 

Albert St., Toronto, Can. 

Burton Holmes Lectures, Inc., 7512 
N. Ashland Ave., Chicago, 111. 
DEPUE, O. B. (M) 

7512 N. Ashland Ave., Chicago, 111. 

Gevaert Co. of America, Inc., 423 

W. 55th St., New York, N. Y. 

Surya Film Co., 5 Cunningham Rd., 
Bangalore City, Mysore State, 



[J. S. M. P. E. 


Kohinoor Film Co., Dadar, Bom- 
bay, India. 

Pathe Cinema, 6 Rue Francoeur, 

Paris, France. 

7280 Magnolia Ave., Riverside, 


DEVRY, H. H. (M) 
55 E. Wacker Drive, Box 1, Chicago, 

DEWITT, H. N. (A) 

36 Toronto St., Toronto, Can. 

Motion Picture Prod. & Dist. of 
America, Inc., 469 Fifth Ave., New 
York, N. Y. 
DICKSON, R. B. (4) 

Pyrene Mfg. Co., 560 Belmont Ave., 

Newark, N. J. 

Pathe Studios, Culver City, Calif. 
DIDIEE, L. J. J. (-4) 

Societe Kodak-Pathe, 39 Ave. Mon- 
taigne, Paris, France. 

1832 N. Gower St., Hollywood, 


National Theater Supply Co., 211 

Columbus Ave., Boston, Mass. 

494 Dwas Line Road, Clifton, N. J. 

Metro - Goldwyn - Mayer Studios, 

Culver City, Calif. 

4129 Kingsbury Ave., Toledo, Ohio. 

17, Parkside Drive, Cassiobury Park, 

Watford, Herts, England. 

Menlo Park, Calif. 
DOWNES, A. C. (M) 
National Carbon Co., Box 400, 
Cleveland, Ohio. 

Leeds & Northrup Co., 4901 Stenton 

Ave., Philadelphia, Pa. 
RKO Studios, Inc., 780 Gower St., 

Hollywood, Calif. 
RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

Bell & Howell Co., 1801 Larchmont 

Ave., Chicago, 111. 
Fairmont Theater, Fairmont, W. 


W. H. Hoedt Studios, 212 W. Wash- 
ington Square, Philadelphia, Pa. 

Patent Research, Inc., 521 Fifth 

Ave., New York, N. Y. 
Champion Mfg. Co., 7348 Kimbark 

Ave., Chicago, 111. 

Dunning Process Co., 932 N. La- 

Brea Ave., Hollywood, Calif. 

Dunning Process Co., 932 N. La- 

Brea Ave., Hollywood, Calif. 

21 Martin St., Paterson, N. J. 

RCA Victor Co., Inc., Camden, N. J. 

Eastman Kodak Co., 343 State St., 

Rochester, N. Y. 

Duplex Motion Picture Industries, 
Inc., Sherman St. & Harris Ave., 
Long Island City, N. Y. 


Eastman Kodak Co., Rochester, 

N. Y. 

Thomas A. Edison, Inc., West 
Orange, N. J. 

April, 1931] 



EDISON, THOMAS A. (Honorary) 

West Orange, N. J. 

Paramount Publix Corp., 5451 Mara- 
thon Ave., Hollywood, Calif. 
49 Trafalgar Square, Lynbrook, L. I., 

N. Y. 

Engr. Dept., National Lamp Works, 

Nela Park, Cleveland, Ohio. 
34 Marine Terrace, Aberystwyth, 


Peko, Inc., 2400 W. Madison St., 

Chicago, 111. 

10 Westbury Ave., Staten Island, 

N. Y. 

Felms Revo Corp., P. O. Box 182, 

Staten Island, N. Y. 

197 Queens Gate, London, S. W. 7, 


4 Chatsworth, Riverdale Rd., Twick- 
enham Park, Middlesex, Eng- 

907 W. Hamilton St., Flint, Mich. 

Audio-Cinema, Inc., 2826 Decatur 
Ave., Long Island City, N. Y. 

Cinema Traders, Ltd., 26 Church St., 
Charing X Rd., London, W. 1, 

97 Bismarkstrasse, Berlin Charlot- 

tenburg, Germany. 

RCA Victor Co., Inc., Camden, 

N. J. 

Vitaphone Corp., 1277 E. 14th St., 
Brooklyn. N. Y. 


Fox Film Corp., 444 West 56th St., 

New York, N. Y 

Division of Motion Pictures, U. S. 
Dept. of Agriculture, Washington, 
D. C. 

Gaisford House, Gaisford St., Ken- 
tish Town, London, N. W. 5, 


Archibald Nettlefold Productions, 
The Studios, Hurst Grove, Wal- 
ton-on-Thames, England. 

3225 93rd St., Jackson Heights, 

L. L, N. Y. 

Kodak, S. P. z. o. o. 5 Place Na- 
poleon, Warsaw, Poland. 

Engr. Dept., National Lamp Works, 

Nela Park, Cleveland, Ohio. 

Paramount Publix Corp., Para- 
mount Bdg., New York, N. Y. 

Kodak-Pathe, Casilla de Correo 

7353, Buenos Aires, Argentina. 

Providence Engineering Works, 521 
S. Main St., Providence, R. I. 

Fearless Camera Co., 7160 Santa 
Monica Blvd., Hollywood, Calif. 
2010 Sixth Ave., Los Angeles, 


Chicago Film Lab., Inc., 1322 Bel- 

mont Ave., Chicago, 111. 

40 Seventh Ave., New York, N. Y. 

Paramount Publix Corp., 35-11 35th 
Ave., Long Island City, N. Y. 



[J. s. M. p. E. 

FISCHER, J. (4) 

Capitol Theatres, Ltd., Singapore, 


3329 S. Western Blvd., Chicago, 111. 
Kodak, Ltd., Wealdstone, Middle- 
sex, England. 

Tri-State Motion Pictures Co., 208 

Film Bldg., Cleveland, Ohio. 

Electrical Research Products, Inc., 
250 W. 57th St., New York, N. Y. 

Fleischer Studios, Inc., 1600 Broad- 
way, New York, N. Y. 

204 Maple St., Windsor, Ont., Can. 

Fox Film Corp., 850 Tenth Ave., 

New York, N. Y. 
FLORY, Louis P. (4) 

Boyce-Thompson Institute, 1086 N. 

Broadway, Yonkers, N. Y. 

Celluloid Co., 290 Ferry St., Newark, 

N. J. 

Bell & Howell Co., 1801 Larchmont 

Ave., Chicago, 111. 

3 Belmont House, Candover St., 

London, W. 1, England. 

The Turning, Kinsbourne Green, 

Harpden, Herts, England. 

RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

Hughes Franklin Theatres, 7051 
Hollywood Blvd., Los Angeles, 

Electrical Research Products, Inc., 
7040 Hollywood Blvd., Los An- 
geles, Calif. 


Fox Film Corp., 850 Tenth Ave., 

New York, N. Y. 

216 W. Water St., Milwaukee, Wis. 

1533 N. Stanley Ave., Hollywood, 


British International Pict., Ltd., 

Elstree, Herts, England. 

Eastman Kodak Co., 343 State 

Street, Rochester, N. Y. 
FULCHER, E. J. 04) 

157 Albert St., East, Sault Ste. 

Marie, Ont., Canada. 
FULTON, C. H. (A) 

E. E. Fulton Co., 1018 3. Wabash 
Ave., Chicago, 111. 


Corning Glass Works, Corning, N. Y. 
GAGE, OTIS A. (4) 

Corning Glass Works, Corning, N. Y. 
GARLAND, R. M. (4) 

Division 35, U. S. Patent Office, 

Washington, D. C. 

Gaumont Co., 3 Rue Caulaincourt, 

Paris, 18 me, France. 
GEIB, E. R. (M) 

National Carbon Co., Box 400, 

Cleveland, Ohio. 
GELMAN, J. N. (M) 

3439 Jay St., Cincinnati, Ohio. 

1 Trevanion Rd., West Kensing- 
ton, London, W. 14, England. 

E. S. S. Colour Filter Co., 1 Monta- 
gue St., London, W. C. 1, England. 

J. E. Brulatour, Inc., 154 Crescent 

St., Long Island City, N. Y. 

46 Jayson Ave., Great Neck, L. I., 
N. Y. 

April, 1931] 




Geyer-Werke, A.-G., Harzerstrasse 
39/42, Berlin, S. O. 36, Germany. 
GEYER, KARL H. (^4) 

32 Westbourne Terrace, London, W. 

2, England. 

Admiralstrasse 2/3, Zeuthen i/Mark, 


J. E. Brulatour, Inc., 6700 Santa 
Monica Blvd., Hollywood, Calif. 
J. L. Nerlien, Ltd., Nedre slotsgats 

13, Oslo, Norway. 

Visual Instruction Section, General 
Electric Co., Schenectady, N. Y. 

Warner Brothers Theatres, 932 F. 
St., N. W., Washington, D. C. 

6318 24th Ave., Brooklyn, N. Y. 

14 N. Hancock St., Lexington, 


Electrical Research Products, Inc., 
712 Union Trust Bldg., Cleveland, 

Abbey House, Westminster, London, 

S. W. 1, England. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 
GOLDBERG, Jos. H. (M] 

Publix Theaters Corp., Paramount 

Bldg., New York, N. Y. 

Motion Picture Division, U. S. Dept. 
of Commerce, Washington, D. C. 
Audio-Cinema, Inc., 2826 Decatur 

Ave., New York, N. Y. 
RCA Photophone, Inc., 411 Fifth 
Ave., New York, N. Y. 


104 Bittman St., Akron, Ohio. 

Pacent Electric Co., 91 Seventh Ave., 

New York, N. Y. 

Standard Kine Labs., Inc., Rythe 
Works, Thames-Ditton, England. 

Engr. Dept., Camera Works, East- 
man Kodak Co., Rochester, N. Y. 
GREEN, W. C. (M) 
288 Belvedere Rd., Burton-on-Trent, 


2722 Harriet Ave., S. Minneapolis, 


4531 S. 169th St., Flushing, L. I., 

N. Y. 

76 Echo Ave., New Rochelle, N. Y. 

International Projector Corp., 90 

Gold St., New York, N. Y. 
6417 W. 6th St., Los Angeles, 


1 Wirral St., Birkenhead, England. 

Western Electric Co., Old Colony 
House, South King St., Man- 
chester, England. 

Radio Corporation of America, 233 

Broadway, New York, N. Y. 
GUERIN, A. J. (M} 

Bennett Film Laboratories, 6363 
Santa Monica Blvd., Hollywood, 

6 Sibley Place, Rochester, N. Y. 

Bijou Theater, Bangor, Maine. 


9 Argyle Road, Brooklyn, N. Y. 



[J. S. M. P. E. 


National Theatre Supply Co., 308 

N. Gay St., Baltimore, Md. 

Philips' Glow Lamps Works, Ltd., 

Eindhoven, Holland. 

Kodak, Ltd., Wealdstone, Middle- 
sex, England. 

British International Pictures, Ltd., 

Elstree, Herts, England. 
HAMMOND, Louis E. (4) 

Brooklyn Strand Theater, 647 Fulton 

St., Brooklyn, N. Y. 

National Carbon Co., Inc., 841 E. 
Fourth Place, Los Angeles, Calif. 

Research Dept., Westinghouse Elec- 
tric & Mfg. Co., E. Pittsburgh, Pa. 

1835 N. Garfield PI., Apt. A., Holly- 
wood, Calif. 

Paramount Publix Corp., 5451 Mara- 
thon St., Hollywood, Calif. 

2825 Linden Ave., Knoxville, Tenn. 
HARDY, A. C. (A) 

Mass. Institute of Technology, Cam- 
bridge, Mass. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

Electrical Research Products, Inc., 

195 Broadway, New York, N. Y. 

3038 Richmond Blvd., Oakland, 


15 Charlotte St., London, W. 1, 


Stoll Picture Productions, Ltd., Stoll 
Studios, Temple Rd., Cricklewood, 
London, N. W. 2, England. 


Paramount Publix Corp., 5451 Mara- 
thon St., Hollywood, Calif. 
Debrie Etablissemente, 23 Morti- 
mer St., London, W. 1, Eng- 
HAYDEN, A. C. (M) 

A. C. Hayden Co., Box 496, Brock- 
ton, Mass. 

P. O. Box 69, Brockton, Mass. 

11 George St., Brooklyn, N. Y. 

Colornim Corp., 122 E. 42nd St., 

New York, N. Y. 

1747 N. Mayfield Ave., Chicago, 


Hewitson, Ltd., Windsor Theatre, 

Smethwick, Staffs., England. 
Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 

119 Darley Rd., Randwick, Sydney, 


69 Gouett St., Randwick, Sydney, 


24 Holyrood Rd., East Barnet, 

Herts, England. 

12 E. 44th St., New York, N. Y. 

Metropolitan Motion Picture Co. : 
2310 Cass Ave., Detroit, Mich. 

Alliance Studios, St. Margarets, 

Twickenham, England. 

The Gaumont Co., Ltd., Lime Grove, 
Shepherds Bush, London, W. 12, 

April, 1931] 




Hochstetter Research Lab., Bene- 

dum Trees Bldg., Pittsburgh, Pa. 

37, Woodbastwick Rd., Lower 
Sydenham, S. E. 26, London, 

5319 Santa Monica Blvd., Los 

Angeles, Calif. 
HOFFMAN, Louis B. (M) 

Blind Brook Lodge, Rye, N. Y. 

Pathe Audio Review, 35 W. 45th 

St., New York, N. Y. 

Bell Telephone Labs., Inc., 463 

West St., New York, N. Y. 

315 W. 86th St., New York, N. Y. 

15 S. Oraton Parkway, East Orange, 

N. J. 

29-41 167th St., Flushing, L. I., 

N. Y. 

Chenango Valley Savings Bank Bldg., 

Binghamton, N. Y. 

Kiddle, Margeson, & Hornidge, 511 

Fifth Ave., New York, N. Y. 
Warner Bros. Pictures, 321 W. 44th 

St., New York, N. Y. 
General Radio Cd., 30 State St., 

Cambridge, Mass. 
HOWELL, A. S. (M) 

Bell & Howell Co., 1801 Larchmont 

Ave., Chicago, 111. 

Akeley Camera, Inc., 175 Varick St., 

New York, N. Y. 

General Electric Co., Schenectady, 
N. Y. 


RCA Photophone, Inc., 411 Fifth 
Ave., New York, N. Y. 


Consolidated Film Industries, 1776 

Broadway, New York, N. Y. 

111 W. 5th St., Plainfield, N. J. 

Selo, Ltd., Woodman Road, Warley, 

Brentwood, Essex, England. 

RCA Photophone, Inc., 438 W. 37th 

St., New York, N. Y. 

The Adcraft Film Service, 1312 

Oswego St., Utica, N. Y. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

Eastman Kodak Co., 6706 Santa 
Monica Blvd., Hollywood, Calif. 

Eastman Kodak Co., 350 Madison 
Ave., New York, N. Y. 


Paramount - Famous - Lasky Lab., 
1546 N. Argyle Ave., Hollywood, 

Electronics, 36th St. and 10th Ave., 

New York, N. Y. 

Electrical Research Products, Inc., 
250 West 57th St., New York, 
N. Y. 
IVES, F. E. (Honorary) 

1753 N. 15th St., Philadelphia, Pa. 

Pathescope Co. of America, Inc., 
33 W. 42nd St., New York, N. Y. 


The Optical Institute, Bizjevaya 
Linia 12, Leningrad, U. S. S. R. 



[J. S. M. P. E. 

JAMES, F. E. (M) 

General Electric Co., 5201 Santa F 

Ave., Los Angeles, Calif. 

1801 Vz Commerce St., Dallas, Texas. 

Metropolitan Motion Picture Co., 
2310 Cass Ave., Detroit, Mich. 

Jay's Screen Service, 23 Nithsdale 

Rd., Glasgow, S. 1, Scotland. 

9 Giles St., Toorak, Adelaide, South 


5502 16th St., Washington, D. C. 

Jenkins & Adair, Inc., 3333 Belmont 

Ave., Chicago, 111. 

20 New St., St. Martins Lane, 

London, W. C. 2, England. 

Zeiss-Ikon A.-G., Schandauerstrasse, 

76, Dresden a 21, Germany. 

West End Plaza & West End Ave., 

Long Branch, N. J. 

National Bank Bldg., Johannesburg, 

South Africa. 

518 W. Maumee St., Angola, In- 


Bausch & Lomb Optical Co., 28 
Geary St., San Francisco, Calif. 

Eastman Kodak Co., Kodak Park, 

Rochester, N. Y. 
433 Beaumont Ave., Charlotte, 

JONES, L. A. (M) 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 

12 Fairview Ave., Yonkers, N. Y. 


Technicolor Motion Picture Corp., 
823 N. Seward St., Hollywood, Cal. 

P. O. Box 929, Harrisburg, Pa. 

Western Electric Co., Ltd., Bush 
House, Aldwych, London, Eng. 

1310 S. Van Ness St., Los Angeles, 

KELLEY, WM. V. D. (M) 

2228 Holly Drive, Hollywood, Calif. 

RCA Victor Co., Inc., Camden, 


A. Kershaw & Son, 300 Harehills 

Lane, Leeds, England. 

32 Farley Rd., Scarsdale, N. Y. 

Keuffel & Esser Co., 3rd & Adams 

Sts., Hoboken, N. J. 

48 Gova Chand Rd., Entally, Cal- 
cutta, India. 


Technicolor Motion Picture "Corp.. 
823 N. Seward St., Hollywood, 


National Screen Service, Ltd., 25 
Denmark St., London, W. C. 2, 

36 Crestwood Ave., Buffalo, N. Y. 
27, The Chase, Watford, Herts, 


Society for Visual Education, 327 

LaSalle St., Chicago, 111. 

Visual Instruction Section, General 
Electric Co., Schenectady, N. Y. 

April, 1931] 




Electrical Research Products, Inc., 
250 W. 57th St., New York, N. Y. 


Stanley Co. of America, llth & 

Market Sts., Philadelphia, Pa. 

Publix Theaters Corp., Paramount 

Bldg., New York, N. Y. 

16 Rue de Chateaudun, Asnieres 

(Seine), France. 

Riverbank Laboratories, Geneva, 111. 

Friedrichstrasse 46, Berlin, S. W. 68, 


406 Belleville Ave., Belleville, N. J. 

609 Nineteenth St., Monroe, Wis. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 
.5412 Virginia Ave., Hollywood, Calif. 


National Carbon Co., P. O. Box 
400, Cleveland, Ohio. 


Westinghouse Lamp Co., Bloomfield, 
N. J. 


1736 N. Orange Drive, Hollywood, 


Duplex M. P. Industries, Inc., Long 

Island City, N. Y. 
LAIR, C. (M) 

Kodak-Pathe, 30 Rue des Vignerons, 

Vincennes (Seine), France. 

Bell & Howell Co., Ltd., 320 Regent 

St., London, W. 1, England. 

Metro - Goldwyn - Mayer Studios, 
Culver City, Calif. 


2334 Crenshaw Blvd., Los Angeles, 


Audio-Cinema, Inc., 2826 Decatur 

Ave., New York, N. Y. 
LANG, C. J. (M) 

Lang Mfg. Works, Olean, N. Y. 

National Theater Supply Co., 624 S. 

Michigan Ave., Chicago, 111. 

RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

Paramount Publix Corp., 1501 

Broadway, New York, N. Y. 

5255 N. Hoyne Ave., Chicago, 111. 

Paramount Publix Corp., 1501 

Broadway, New York, N. Y. 

327 Washington Ave., Miami Beach, 


Pathe Exchange, 1926 S. Vermont 

Ave., Los Angeles, Calif. 

Lawley Apparatus Co., Ltd., 26 
Church St., Charing X Road, 
London, W. 1, England. 

General Business Films, Inc., 415 
Lexington Ave., New York, 
N. Y. 

Fox Films, 1401 N. Western Ave., 

Los Angeles, Calif. 

Akeley Camera Co., 175 Varick St., 

New York, N. Y. 

Arcturus Radio Tube Co., 260 Sher- 
man Ave., Newark, N. J. 

6019 Eileen St., Los Angeles, 



[J. S. M. P. E. 

LICHTE, H. (Jlf) 

Forschungsinstitut der A. E. G., 

Berlin, Germany. 

Celluloid Corp., 36 Aldermanbury, 

London, E. C. 2, England. 

15 Catherine Rd., Surbiton, Surrey, 


Herbert & Huesgen Co., 18 E. 42nd 

St., New York, N. Y. 

The Replitura Corp., Melrose Ave., 

Stamford, Conn. 
LITTLE, W. F. (M) 

Electrical Testing Lab., 80th St. & 
East End Ave., New York, 
N. Y. 

135 William St., New York, N. Y. 

RCA Victor Co., Inc., Camden, 

N. J. 

RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 

British - Thomson - Houston Co., 

Ltd., Rugby, England. 

31 Manor Ave., Hounslow, West 

Middlesex, England. 

Suresh Film Co., Ltd., Dadar Main 
Road, Dadar, Bombay, 14, India. 

Warner Bros. Pictures, 13-14 New- 
man St., London, W. 1, England. 

Publix Granada Theatre, 6427 Sheri- 
dan Rd., Chicago, 111. 
LUMIERE, Louis (Honorary) 

156 Blvd. Bineau a Neuilly, Paris, 


I. G. Farbenindustrie Aktiengesell- 
schaft, Berlin, S. O. 36, Germany. 

Pacent Reproducer Corp., 91 
Seventh Ave., New York, N. Y. 

A. R. Maas Chemical Co., 308 E. 
Eighth St., Los Angeles, Calif. 

Vitaphone Corp., 1277 E. 14th St., 

Brooklyn, N. Y. 

Electrical Research Products, Inc., 
7046 Hollywood Blvd., Los 
Angeles, Calif. 

Metro - Goldwyn - Mayer Pictures, 
1540 Broadway, New York, N. Y. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

Piroj Bldgs., 171 Dharamtala St., 

Calcutta, Br. India. 

5640 Kingsessing Ave., Philadelphia, 


UFA Films, Inc., 1540 Broadway, 

New York, N. Y. 

Malkames Educational Film Co., 705 
W. Diamond Ave., Hazelton, Pa. 

12 E. 85th St., New York, N. Y. 

91 Prospect St., East Orange, N. J. 

E. J. Electrical Installation Co., 
227 E. 45th St., New York, N. Y. 
MANLEY, R. G. H (A) 

P. O. Box 772, Auckland, New 


1923 81st St., Brooklyn, N. Y. 

April, 1931] 




168 Rue de Belleville, Paris, 20e, 


Pathe Cinema, 8 Rue Leconte de 

Lisle, Paris, France. 

Visugraphic Pictures, Inc., 247 Park 

Ave., New York, N. Y. 

8770 Shoreham Drive, West Los 
| Angeles, Calif. 


Technical Division, Hercules Pow- 
der Co., Wilmington, Del. 

1752 Atlantic Ave., Brooklyn, N. Y. 

Electrical Research Products, Inc., 
250 W. 57th St., New York, 
N. Y. 

Eclair Tirage 34 a 42 Av. d'Enghein, 

Epinay sur Seine, France. 

327 23rd St., Miami Beach, Fla. 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 

P. O. Box 1629, Manila, P. I. 

National Carbon Co., 599 Eighth St., 

San Francisco, Calif. 

Electrical Research Products, Inc., 
250 W. 57th St., New York, 
N. Y. 

Super Lab. Corp., 233 W. 42nd St., 

New York, N. Y. 

McAuley Mfg. Co., 552 W. Adams 

St., Chicago, 111. 

Western Electric Co. of Australia, 
Ltd., 250 Pitt St., Sydney, Aus- 


Westinghouse Elec. & Mfg. Co., 
150 Broadway, New York, N. Y. 

916 St. James St., Pittsburgh, Pa. 
McCoY, JAMES L. (A) 

Westinghouse Lamp Co., Bloomfield, 
N. J. 


West Coast Theaters, Inc., Washing- 
ton & Vermont Aves., Los Angeles, 

Agfa, Ltd., Vintry House, Iveen St., 
Place, London, E. C. 4, England. 
McGiNNis, F. J. (A) 

Box 2387, Palm Beach, Fla. 

Fox Theater, 2211 Woodward Ave., 

Detroit, Mich. 

International Projector Corp., 90 

Gold St., New York, N. Y. 

Kodak Park Works, Eastman Kodak 

Co., Rochester, N. Y. 
McNABB, J. H. (M) 

Bell & Howell Co., 1801 Larchmont 

Ave., Chicago, 111. 

36 Gilbert St., Watertown, Mass. 
McNicoL, DONALD (.4) 

Projection Engineering, 52 Vander- 

bilt Ave., New York, N. Y. 

99 Melrose St., Melrose, Mass. 

Albrechtstrasse 60A, Berlin-Sudende, 


395 Madrona Lane, Bel-Air, Los 

Angeles, Calif. 
MEES, C. E. K. (M) 

Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 
Suresh Film Co., Ltd., Dadar Main 
Rd., Dadar, Bombay, 14, India. 



[J. S. M. p. E. 

Trans-Lux Movies Corp., 247 Park 

Ave., New York, N. Y. 

Messter Optikon G.m.b.h., Am Karls- 
bad 16, Berlin, W. 35, Germany. 

Parkstrasse, 56/58 Berlin- Dahlem, 


Associated Screen News, Ltd., Wes- 
tern Ave. & Delcarie Blvd., Mon- 
treal, Que., Canada. 

Agfa Ansco Corp., Binghamton, 
N. Y. 


Makino Productions, Myoshinji 
Kyoto Shigai, Kyoto Prefecture, 

1788 Amsterdam Ave., New York, 

N. Y. 

Lyon & Lyon, National City Bank 

Bldg., Los Angeles, Calif. 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

47 Westfield Ave., East Roselle 

Park, N. J. 

United Research Corp., 39th St. & Van 
Pelt Ave., Long Island City, N. Y. 

Metro-Goldwyn-Mayer, Culver City, 

MISTRY, D. L. (M) 

24 Nepean Road, Malabar Hill, 

Bombay, 6, India. 
MISTRY, M. L. (M) 

24 Nepean Road, Malabar Hill, 

Bombay, 6, India. 

Mitchell Camera Corp., 655 N. 
Robertson Blvd., W. Hollywood, 


Bell & Howell Co., 1801 Larchmont 

Ave., Chicago, 111. 
MOLE, P. (M) 

Mole-Richardson, Inc., 941 N. Syca- 
more Ave., Hollywood, Calif. 
MORENO, R. M. (A) 

DuPont-Pathe Film Mfg. Corp., 

Parlin, N. J. 

Electrical Research Products, Inc., 
7046 Hollywood Blvd., Los 
Angeles, Calif. 

606 W. Elm St., Urbana, 111. 
MORTON, H. S. (M) 

3787 Chicago Blvd., Detroit, Mich. 

R. F. D. No. 7, Knoxville, Tenn. 

DuPont-Pathe Film Mfg. Corp., 
35 W. 45th St., New York, N. Y. 

Vitaphone Corp., 5842 Sunset Blvd., 

Hollywood, Calif. 

2629 Calhoun St., New Orleans, La. 

3148 O St., N. W., Washington, D. C. 

British International Pictures, Ltd., 
Elstree, Herts, England. 


D. Nagase & Co., Ltd., Itachibori- 
Minamidori-Nishiku,Osaka, Japan . 

Aunpchand Nanda, Thapar Ganj, 
Rawalpindi Cant, Punjab, India. 

National Cash Register Co., Dayton, 


Neumade Products Corp., 654 Michi- 
gan Ave., Buffalo, N. Y. 

Neumade Products Corp., 442 W. 
42nd St., New York, N. Y. 

April, 1931] 




2 Salisbury Road, Highgate Hilf, 

London, N. 19, England. 

Gaumont British Picture Corp., Ltd., 
New Gallery House, 123 Regent 
St., London, S. W., England. 

Phi Gamma Delta Club, 106 W. 56th 

St., New York, N. Y. 

Metro - Goldwyn - Mayer Studios, 

Culver City, Calif. 

United Research Corp., 39th St. & 
Van Pelt Ave., Long Island City, 
N. Y. 

Korting & Mathiesen Electrical, 
Ltd., 711 Fulham Road, London, 
S. W. 6, England. 

9 Manor Park Gardens, Edgeware, 

Middlesex, England. 

Bausch & Lomb Optical Co., Ro- 
chester, N. Y. 

Fox-Hearst Corp., 460 W. 54th St., 
New York, N. Y. 


Allgemeine Elektricitats-Gesellschaft 
Friedrich Karl-Ufer 2/4, Berlin, 
N. W. 40, Germany. 

Loucks & Norling, 245 W. 55th St., 

New York, N. Y. 

Associated Screen News of Canada, 
Ltd., Western Ave. & Delcarie 
Blvd., Montreal, Que., Canada. 


DuPont-Pathe Film Mfg. Corp., 

Parlin, N. J. 

British & Dominion Film Studios, 
Boreham Wood, Herts, England. 


Cinema Studios Supply Corp., 1438 
N. Beachwood Drive, Hollywood, 

541 Orange Drive, Los Angeles, Calif. 

National Theater Supply Co., 2310 

Cass Ave., Detroit, Mich. 

Taylor, Taylor & Hobson, Ltd., 74 
Newman St., London, W. 1, Eng. 

RCA Photophone, Inc., 411 Fifth 

Ave., New York, N. Y. 

131 Nagle Ave., New York, N. Y. 


"Hilton" North Drive, Ruislip, 

Middlesex, England. 

Hughes Development Co., Ltd., 
1001 N. Orange Drive, Los 
Angeles, Calif. 
OTT, HARRY G. (4) 

Spencer Lens Co., 19 Doat St., 

Buffalo, N. Y. 

Les Studios Paramount, 7 Rue Reser- 
voir, St. Maurice, Seine, France. 

2647 Broadway, New York, N. Y. 

PACENT, Louis G. (M) 

Pacent Reproducer Corp., 91 
Seventh Ave., New York, N. Y. 
PAGE, Louis I. (A) 

RKO Studios, Inc., 780 Gower St., 

Hollywood, Calif. 
PALMER, M. W. (M} 

Paramount Publix Corp., 35-11 35th 
Ave., Long Island City, N. Y. 

Pacent Electric Co., 91 Seventh Ave. 

New York, N. Y. 

Studio Film Labs., Ltd., 80 Wardour 
St., London, W. 1, England. 



[J. S. M. P. E. 


University Theater, Cambridge, 


Krishna & Gujrat Studios, 162 Dadar 

Rd., Dadar, Bombay, India. 

Ontario Govt. M. P. Bureau, Parlia- 
ment Bldg., Toronto, Canada. 

Multicolor, Ltd., 8 S. Michigan 

Ave., Chicago, 111. 

3 Rupert St., London, W. 1, England. 

309 W. Douglas Ave., Wichita, 

PECK, WM. H. (M) 

Colorcraft Corp., 122 E. 42nd St., 

New York, N. Y. 

Westinghouse Elec. & Mfg. Co., 1216 

W. 58th St., Cleveland, Ohio. 
PENROD, A. G. (A) 

1770 E. 26th St., Brooklyn, N. Y. 

44 Whitehall St., New York, N. Y. 

I. G. Farbenindustrie Aktiengesell- 
schaft, Kinotechnische Abteilung, 
Berlin, S. O. 36, Germany. 
Motion Picture Service, Inc., 735 
Arlington Ave., St. Petersburg, 

103 Irving Terrace, Kenmore, N. Y. 
PHELPS, L. G. (M} 

Phelps-Films, Inc., 126 Meadow St., 

New Haven, Conn. 

753 Seward St., Hollywood, Calif. 

Peko, Inc., 2400 W. Madison St., 

Chicago, 111. 
PIROVANO, Louis (A) 

Publix Theaters Corp., 60 Scollay 
Square, Boston, Mass. 


83 Al. Yerozolimska, Warsaw, Poland. 

Western Electric Co., Ltd., Bush 
House, Aldwych, London, W. C. 
2, England. 

1626 N. Crescent Heights, Holly- 
wood, _ Calif. ^ , NJ^ - ^-r- .. 
POMMIER, R. M. B. (M) 

Ste. Francaise Cinechromatique 24, 
Rue de la Pepiniere, Paris, 8e, 

Paramount Publix Corp., 35-11 35th 
Ave., Long Island City, N. Y. 
PORTER, C. D. (A) 

Publix Theaters Corp., 57 Ellis St., 

N. E., Atlanta, Ga. 

Engr. Dept., General Electric Co., 

Nela Park, Cleveland, Ohio. 

Pacent Reproducer Corp., 91 
Seventh Ave., New York, N. Y. 

Warner Research Lab., 461 Eighth 

Ave., New York, N. Y. 
PRESIDENT, THE (Honorary) 

Die Deutsche Kinotechnische Gesell- 
schaft, Lindenstrasse, 26, Berlin, 
S. W. 68, Germany. 
PRESIDENT, THE (Honorary) 

Royal Photographic Society, 35, 
Russell Square, London, W. C. 1, 
PRESIDENT, THE (Honorary) 

Societe Francaise de Photographic, 
Rue de Clichy, 51, Paris, Aeme, 

Bell Telephone Labs., Inc., 463 West 

St., New York, N. Y. 

Burmese Favourite Co., 51 Sule 
Pagoda Road, Rangoon, Burma. 
39 S. LaSalle St., Chicago, 111. 

April, 1931] 



PULVER, M. (Af) 

Duncan Watson & Co., 62 Berners 
St., London, W. 1, England. 


Allison House, Woodlands Rd. f 

Isleworth, Middlesex, England. 

Fox Film Corp., 1401 Northwestern 
Ave., Hollywood, Calif. 


M. Rabinowitz & Sons, Inc., 1373 

Sixth Ave., New York, N. Y. 

8533 Pickford Blvd., Los Angeles, 

RAESS, H. F. (A) 

Warner Research Laboratory, 461 
Eighth Ave., New York, N. Y. 

604 N. Walden Ave., Beverly Hills, 


Motion Picture Herald, 1790 Broad- 
way, New York, N. Y. 
Societa Anonima Italiana Cinema 
Educative, 37 Piazza, Poll, Rome, 

RAVEN, A. L. (M) 
Raven Screen Corp., 147 E. 24th St., 

New York, N. Y. 

Ray-Bell Films, Inc., 817 University 

Ave., St. Paul, Minn. 
35 Grosvenor Place, London, S. W. 1, 


Bausch & Lomb Optical Co., Ro- 
chester, N. Y. 

The Unicorn Hotel, Altringham, 

Cheshire, England. 

Kodak, Ltd., Wealdstone, Middle- 
sex, England. 


156 King St., W., Toronto, Canada. 

Rotherstrasse 20-23, Berlin O. 17, 


1605 N. Cahuenga Ave., Hollywood, 


RCA Victor Co., Inc., Camden, N. J. 

Renier Mfg. Co., 2216 State St., 

Milwaukee, Wis. 
RENWICK, F. F. (4) 

British Photo Plates & Papers, Ltd., 
Rodenside Laboratory, Ilford, 
Essex, England. 

Projection Optics Co., Inc., 330 

Lyell Ave., Rochester, N. Y. 

Williams, Rich, & Morse, 225 Broad- 
way, New York, N. Y. 

97 Rue Lemercier, Paris, 17emc, 


Mole-Richardson, Inc., 941 N. Syca- 
more Ave., Hollywood, Calif. 

43-28 39th Place, Long Island City, 

N. Y. 

39-41 58th St., Woodside, L. L, N. Y. 

Weston Electrical Instrument Corp., 
614 Frelinghuysen Ave., Newark, 
N. J. 

1440 Broadway, New York, N. Y. 

Chester, N. J. 

14 Mayfield Ave., North Finchley, 

London, N. 9, England. 

Bell Telephone Labs., Inc., 463 West 
St., New York, N. Y. 



[J. S. M. p. E. 


1352 University Ave., New York, 

N. Y. 
ROEMEF, H. H. (M) 

Lake Shore Towers, Apt. 12, North, 
3920 Lake Shore Drive, Chicago, 

"Cluny" Deacons Hill Road, Elstree, 

Herts, England. 

Picture Service Corp., 74 Sherman 
St., at Harris Ave., Long Island 
City, N. Y. 

Ilex Optical Co., 726 Portland Ave., 

Rochester, N. Y. 

31 rua Manuel Nobrega, Sao Paulo, 


Engineering Dept., General Electric 
Co., Nela Park, Cleveland, Ohio. 

Cinema Studios Supply Corp., 1438 
Beachwood Drive, Hollywood, 

Kodak A.-G., Markgrafenstrasse 

7-6, Berlin, Germany. 

Publix Theaters Corp., 60 Scollay 
Square, Boston, Mass. 


Rockefeller Institute, 66th St. & 

Ave. A., New York, N. Y. 

Kodak S. P. z. o. o., Place Napoleana 

5, Warsaw, Poland. 

H. E. R. Laborato